Search results
Search for "DBU" in Full Text gives 314 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
DMAP-assisted sulfonylation as an efficient step for the methylation of primary amine motifs on solid support
- Johnny N. Naoum,
- Koushik Chandra,
- Dorit Shemesh,
- R. Benny Gerber,
- Chaim Gilon and
- Mattan Hurevich
Beilstein J. Org. Chem. 2017, 13, 806–816, doi:10.3762/bjoc.13.81
- challenge our hypothesis collidine was replaced by two SPS compatible bases namely, 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU, pKb ≈ 1.10) which is a stronger base than collidine (pKb ≈ 6.57, Table 1, entry 7) and by DMAP (pKb ≈ 4.48) which is a superior nucleophile (Table 1, entry 8). HPLC analysis of the
- crude demonstrated that replacing collidine with DMAP resulted in a dramatic improvement in the conversion of 1 to 1a (98%) and a significant decrease in the amount of the byproducts (Table 1, entry 8). On the other hand, replacing the collidine by DBU resulted in no conversion of 1 to 1a (Table 1
- , entry 7). To further evaluate the effect of base on the conversion and purity, another study was performed with motif 4 as a model using DBU, DMAP, pyridine, and collidine as additives. HPLC analysis showed that the additive used indeed has an impact on the conversion of 4 to 4a and on the crude purity
Graphical Abstract
Figure 1: Collidine-assisted vs DMAP-assisted N-methylation process on solid support. (A) Collidine-assisted ...
Figure 2: Motifs 1–5 were used as models for the optimization of the N-methylation process. i) Introduction o...
Figure 3: Sulfonylation optimization study. HPLC trace overlay that shows the sulfonylation of motif 4 to yie...
Figure 4: DFT calculations for the reaction of o-NBS-Cl with a) collidine and b) DMAP. The structure of the r...
Figure 5: Methylation of motif 3a to 3b using various reaction conditions. HPLC trace overlay presents the ef...
Figure 6: Optimization of o-NBS removal reaction conditions demonstrated on motif 5b. HPLC trace overlay of i...
Figure 7: HPLC trace overlay and MS analysis of the somatostatin analogue, 1SW-1, which was Nα-methylated on ...
N-Propargylamines: versatile building blocks in the construction of thiazole cores
- S. Arshadi,
- E. Vessally,
- L. Edjlali,
- R. Hosseinzadeh-Khanmiri and
- E. Ghorbani-Kalhor
Beilstein J. Org. Chem. 2017, 13, 625–638, doi:10.3762/bjoc.13.61
- converted to the corresponding vinylthiazolines 38 through the treatment with dithioic acids 37 in the presence of EDCI in dichloromethane. This transformation is believed to occur through a tandem coupling–cyclization reaction. The authors showed that the treatment of 38 with DBU at 0 °C provided thiazoles
Graphical Abstract
Figure 1: Selected examples of bioactive thiazole derivatives.
Figure 2: Some natural sources of thiazoles.
Figure 3: Some important thiazole-based compounds derived from N-propargylamines.
Scheme 1: The synthesis of thiazole-2-thiones 3 through the thermal cyclocondensation of N-propargylamines 1 ...
Scheme 2: (a) One-pot synthesis of 2-benzylthiazolo[3,2-a]benzimidazoles 6 through a base-catalyzed cascade r...
Scheme 3: (a) Synthesis of 2-iminothiazolidines 11 from N-propargylamines 9 and isothiocyanates 10. (b) Synth...
Scheme 4: (a) Synthesis of 2-aminothiazoles 17 through the reaction of ethyl 4-aminobut-2-ynoate salts 15 wit...
Scheme 5: Synthesis of 5-(iodomethylene)-3-methylthiazolidines 27 described by Zhou.
Scheme 6: Mechanism that accounts for the formation of 27.
Scheme 7: Clausen’s synthesis of fluorescein thiazolidines 30.
Scheme 8: Synthesis of multiply substituted thiazolidines 33 from N-propargylamines 32 and blocked N-isothioc...
Scheme 9: (a) Microwave-assisted cyclization of N-propargyl thiocarbamate 34. (b) Synthesis of thiazoles 39 t...
Scheme 10: Synthesis of thiazolidines 42 (42’) from the reaction of β-oxodithioesters 40 (40’) with N-propargy...
Scheme 11: Synthesis of 5-(dibromomethyl)thiazoles 44 via halocyclization of N-propargylamines 43 described by...
Scheme 12: Synthesis of dihydrothiazoles 46 through the treatment of N-propargylamides 45 with Lawesson’s reag...
Scheme 13: Synthesis of thiazoles 49 by treatment of silyl-protected N-propargylamines 47 with benzotriazolylt...
Scheme 14: Mechanism proposed to explain the synthesis of 2,5-disubstituted thiazoles 49 developed by Sasmal.
Scheme 15: Mo-catalyzed cyclization of N-propargylthiocarbamate 50.
Scheme 16: (a) DABCO-mediated intramolecular cyclization of N-(propargylcarbamothioyl)amides 53 to the corresp...
Scheme 17: Proposed mechanism for the generation of the iodine-substituted 4H-1,3-thiazines 56 and 4,5-dihydro...
Scheme 18: Au(III)-catalyzed synthesis of 5-alkylidenedihydrothiazoles 58 developed by Stevens.
Transition-metal-catalyzed synthesis of phenols and aryl thiols
- Yajun Liu,
- Shasha Liu and
- Yan Xiao
Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58
- . In 2013, in the study of the synthesis of (Z)-3-arylthioacrylic acids and thiochromenones, Lee and co-workers found that 89% yield of thiophenol could be directly obtained by Pd (PPh3)2Cl2/dppb (L18) catalyzed coupling reaction of iodobenzene and Na2S·5H2O in the presence of DBU (Scheme 61) [104]. In
Graphical Abstract
Figure 1: Examples of drugs bearing phenol or aryl thiol as central structural motifs.
Scheme 1: Hydroxylation of aryl halides using biphenylphosphine as ligand.
Scheme 2: Hydroxylation of aryl halides using tert-butylphosphine as ligand.
Scheme 3: Hydroxylation of aryl halides using imidazole typed phosphine ligands.
Scheme 4: [Pd(cod)(CH2SiMe3)2] catalyzed hydroxylation of aryl halides.
Scheme 5: Pd/PANI catalyzed hydroxylation of hydroxylation of aryl halides.
Scheme 6: MCM-41-dzt-Pd catalyzed hydroxylation of aryl halides.
Scheme 7: Hydroxylation of aryl halides using dibenzoylmethane as ligand.
Scheme 8: Hydroxylation of aryl halides using 2,2’-bipyridine as ligand.
Scheme 9: Hydroxylation of aryl bromides using imidazolyl pyridine as ligand.
Scheme 10: Hydroxylation of aryl halides using DMEDA as ligand.
Scheme 11: Hydroxylation of aryl halides using PAO as ligand.
Scheme 12: Hydroxylation of aryl halides using D-glucose as ligand.
Scheme 13: Hydroxylation of aryl halides using INDION-770 as ligand.
Scheme 14: PEG-400 mediated hydroxylation of aryl halides.
Scheme 15: Hydroxylation of aryl halides using glycolic acid as ligand.
Scheme 16: Hydroxylation of aryl halides using L-sodium ascorbate as ligand.
Scheme 17: Difunctionalized ethanes mediated hydroxylation of aryl iodides.
Scheme 18: Hydroxylation of aryl halides using 2-methyl-8-hydroxylquinoline as ligand.
Scheme 19: Hydroxylation of aryl halides using 8-hydroxyquinolin-N-oxide as ligand.
Scheme 20: Hydroxylation of aryl halides using lithium pipecolinate as ligand.
Scheme 21: Hydroxylation of aryl halides using L-lithium prolinate.
Scheme 22: Hydroxylation of aryl halides using triethanolamine as ligand.
Scheme 23: CuI-nanoparticle-catalyzed hydroxylation of aryl halides.
Scheme 24: Cu-g-C3N4-catalyzed hydroxylation of aryl bromides.
Scheme 25: Cu(OAc)2-mediated hydroxylation of (2-pyridyl)arenes.
Scheme 26: Removable pyridine moiety directed hydroxylation of arenes.
Scheme 27: Removable quinoline moiety directed hydroxylation of arenes.
Scheme 28: CuCl2 catalyzed hydroxylation of benzimidazoles and benzoxazoles.
Scheme 29: Disulfide-directed C–H hydroxylation.
Scheme 30: Pd(OAc)2-catalyzed hydroxylation of diarylpyridines.
Scheme 31: PdCl2-catalyzed hydroxylation of 2-arylpyridines.
Scheme 32: PdCl2-catalyzed hydroxylation of 2-arylpyridines.
Scheme 33: Pd(OAc)2-catalyzed hydroxylation of 2-arylpyridines.
Scheme 34: Pd(CH3CN)2Cl2-catalyzed hydroxylation of 2-arylpyridines.
Scheme 35: Pd(OAc)2-catalyzed hydroxylation of benzothiazolylarenes.
Scheme 36: Pd(OAc)2 catalyzed hydroxylation of benzimidazolylarenes.
Scheme 37: Dioxane mediated hydroxylation of 2-heteroarylarenes.
Scheme 38: Hydroxylation of oxime methyl ester.
Scheme 39: CN-directed meta-hydroxylation.
Scheme 40: Pd(OAc)2-catalyzed hydroxylation of benzoic acids.
Scheme 41: Pd(OAc)2-catalyzed hydroxylation of biaryl or aryl alkyl ketones.
Scheme 42: Pd(OAc)2 and Pd(TFA)2 catalyzed hydroxylation of aryl ketones.
Scheme 43: Pd(OAc)2 catalyzed hydroxylation of aryl ketones.
Scheme 44: Pd(TFA)2-catalyzed hydroxylation of aryl phosphonates.
Scheme 45: Hydroxy group directed hydroxylation.
Scheme 46: [Ru(O2CMes)2(p-cymene)] catalyzed hydroxylation of benzamides and aryl ketones.
Scheme 47: [RuCl2(p-cymene)]2-catalyzed hydroxylation of benzamides and carbamates.
Scheme 48: [RuCl2(p-cymene)]2 catalyzed hydroxylation of benzaldehydes.
Scheme 49: [RuCl2(p-cymene)]2 catalyzed hydroxylation of ethyl benzoates, benzamides and carbamates.
Scheme 50: Different regioselective ortho-hydroxylation.
Scheme 51: Ruthenium-complex-catalyzed hydroxylation of flavones.
Scheme 52: Vanadium-catalyzed hydroxylation of arenes.
Scheme 53: VOSiW-catalyzed hydroxylation of arenes.
Scheme 54: Synthesis of aryl thiols using thiourea as thiol source.
Scheme 55: Synthesis of aryl thiols using alkyl thiol as thiol source.
Scheme 56: Synthesis of 1-thionaphthol using HS-TIPS as thiol source.
Scheme 57: Synthesis of aryl thiols using sodium thiosulfate as thiol source.
Scheme 58: Synthesis of thiophenol using thiobenzoic acid as thiol source.
Scheme 59: Synthesis of aryl thiols using sulfur powder as thiol source.
Scheme 60: CuI-nanoparticles catalyzed synthesis of aryl thiols.
Scheme 61: Synthesis of aryl thiols using Na2S·5H2O as thiol source.
Scheme 62: Synthesis of aryl thiols using 1,2-ethanedithiol as thiol source.
Pd- and Cu-catalyzed approaches in the syntheses of new cholane aminoanthraquinone pincer-like ligands
- Nikolay V. Lukashev,
- Gennadii A. Grabovyi,
- Dmitry A. Erzunov,
- Alexey V. Kazantsev,
- Gennadij V. Latyshev,
- Alexei D. Averin and
- Irina P. Beletskaya.
Beilstein J. Org. Chem. 2017, 13, 564–570, doi:10.3762/bjoc.13.55
- (6a) is readily aminated by phthalimide using classical Ullmann conditions (15% Cu powder, quinoline, 200 °C in PhNO2) [41]. However, the reaction of 3c with 6a using the same conditions, as well as the addition of stronger bases (DABCO, DIPEA, DBU) afforded extremely low yields (7–12%) of aminated
Graphical Abstract
Figure 1: A tripodal molecular pocket (a) [12] or jellyfish resembling receptors (b) [11,16].
Scheme 1: Example of Pd-catalyzed amination for modification of bile acid derivatives.
Scheme 2: Synthesis of 24-aminocholanols.
Scheme 3: Synthesis of 24-arylaminocholanols by Cu-catalyzed amination.
Scheme 4: Synthesis of 24-arylaminocholanols by Pd-catalyzed amination.
Figure 2: UV–vis spectra of 5c (50 μM solution in MeCN) before and after the addition of 5 equiv of metal per...
Synthesis of 1-indanones with a broad range of biological activity
- Marika Turek,
- Dorota Szczęsna,
- Marek Koprowski and
- Piotr Bałczewski
Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48
- 76% yield. The former 271 was obtained from the trienone 270/270’ which underwent ring closure to give the 6-membered ring [105] (Scheme 76). 2.2 From alkynes DBU and CpRu(PPh3)2Cl dual catalysts enabled a one-pot annulation of aldehyde 273 and cyclopentanone (274) to give the 1-indanone derivative
- rings 3.1 From alkynes The intramolecular, dehydro-Diels–Alder reaction of ketene dithioacetals 302 leading to formation of various benzo[f]-1-indanones 303–305, has been described in 2015 by Bi et al. [117]. Modulation on the reaction parameters such as addition of DBU and the type of atmospheric gas
Graphical Abstract
Figure 1: Biologically active 1-indanones and their structural analogues.
Figure 2: Number of papers about (a) 1-indanones, (b) synthesis of 1-indanones.
Scheme 1: Synthesis of 1-indanone (2) from hydrocinnamic acid (1).
Scheme 2: Synthesis of 1-indanone (2) from 3-(2-bromophenyl)propionic acid (3).
Scheme 3: Synthesis of 1-indanones 5 from 3-arylpropionic acids 4.
Scheme 4: Synthesis of kinamycin (9a) and methylkinamycin C (9b).
Scheme 5: Synthesis of trifluoromethyl-substituted arylpropionic acids 12, 1-indanones 13 and dihydrocoumarin...
Scheme 6: Synthesis of 1-indanones 16 from benzoic acids 15.
Scheme 7: Synthesis of 1-indanones 18 from arylpropionic and 3-arylacrylic acids 17.
Scheme 8: The NbCl5-induced one-step synthesis of 1-indanones 22.
Scheme 9: Synthesis of biologically active 1-indanone derivatives 26.
Scheme 10: Synthesis of enantiomerically pure indatraline ((−)-29).
Scheme 11: Synthesis of 1-indanone (2) from the acyl chloride 30.
Scheme 12: Synthesis of the mechanism-based inhibitors 33 of coelenterazine.
Scheme 13: Synthesis of the indane 2-imidazole derivative 37.
Scheme 14: Synthesis of fluorinated PAHs 41.
Scheme 15: Synthesis of 1-indanones 43 via transition metal complexes-catalyzed carbonylative cyclization of m...
Scheme 16: Synthesis of 6-methyl-1-indanone (46).
Scheme 17: Synthesis of 1-indanone (2) from ester 48.
Scheme 18: Synthesis of benzopyronaphthoquinone 51 from the spiro-1-indanone 50.
Scheme 19: Synthesis of the selective endothelin A receptor antagonist 55.
Scheme 20: Synthesis of 1-indanones 60 from methyl vinyl ketone (57).
Scheme 21: Synthesis of 1-indanones 64 from diethyl phthalate 61.
Scheme 22: Synthesis of 1-indanone derivatives 66 from various Meldrum’s acids 65.
Scheme 23: Synthesis of halo 1-indanones 69.
Scheme 24: Synthesis of substituted 1-indanones 71.
Scheme 25: Synthesis of spiro- and fused 1-indanones 73 and 74.
Scheme 26: Synthesis of spiro-1,3-indanodiones 77.
Scheme 27: Mechanistic pathway for the NHC-catalyzed Stetter–Aldol–Michael reaction.
Scheme 28: Synthesis of 2-benzylidene-1-indanone derivatives 88a–d.
Scheme 29: Synthesis of 1-indanone derivatives 90a–i.
Scheme 30: Synthesis of 1-indanones 96 from o-bromobenzaldehydes 93 and alkynes 94.
Scheme 31: Synthesis of 3-hydroxy-1-indanones 99.
Scheme 32: Photochemical preparation of 1-indanones 103 from ketones 100.
Scheme 33: Synthesis of chiral 3-aryl-1-indanones 107.
Scheme 34: Photochemical isomerization of 2-methylbenzil 108.
Scheme 35: Synthesis of 2-hydroxy-1-indanones 111a–c.
Scheme 36: Synthesis of 1-indanone derivatives 113 and 114 from η6-1,2-dioxobenzocyclobutene complex 112.
Scheme 37: Synthesis of nakiterpiosin (117).
Scheme 38: Synthesis of 2-alkyl-1-indanones 120.
Scheme 39: Synthesis of fluorine-containing 1-indanone derivatives 123.
Scheme 40: Synthesis of 2-benzylidene and 2-benzyl-1-indanones 126, 127 from the chalcone 124.
Scheme 41: Synthesis of 2-bromo-6-methoxy-3-phenyl-1-indanone (130).
Scheme 42: Synthesis of combretastatin A-4-like indanones 132a–s.
Figure 3: Chemical structures of investigated dienones 133 and synthesized cyclic products 134–137.
Figure 4: Chemical structures of 1-indanones and their heteroatom analogues 138–142.
Scheme 43: Synthesis of 2-phosphorylated and 2-non-phosphorylated 1-indanones 147 and 148 from β-ketophosphona...
Scheme 44: Photochemical synthesis of 1-indanone derivatives 150, 153a, 153b.
Scheme 45: Synthesis of polysubstituted-1-indanones 155, 157.
Scheme 46: Synthesis of 1-indanones 159a–g from α-arylpropargyl alcohols 158 using RhCl(PPh3)3 as a catalyst.
Scheme 47: Synthesis of optically active 1-indanones 162 via the asymmetric Rh-catalyzed isomerization of race...
Scheme 48: Mechanism of the Rh-catalyzed isomerization of α-arylpropargyl alcohols 161 to 1-indanones 162.
Figure 5: Chemical structure of abicoviromycin (168) and its new benzo derivative 169.
Scheme 49: Synthesis of racemic benzoabicoviromycin 172.
Scheme 50: Synthesis of [14C]indene 176.
Scheme 51: Synthesis of indanone derivatives 178–180.
Scheme 52: Synthesis of racemic pterosin A 186.
Scheme 53: Synthesis of trans-2,3-disubstituted 1-indanones 189.
Scheme 54: Synthesis of 3-aryl-1-indanone derivatives 192.
Scheme 55: Synthesis of 1-indanone derivatives 194 from 3-(2-iodoaryl)propanonitriles 193.
Scheme 56: Synthesis of 1-indanones 200–204 by cyclization of aromatic nitriles.
Scheme 57: Synthesis of 1,1’-spirobi[indan-3,3’-dione] derivative 208.
Scheme 58: Total synthesis of atipamezole analogues 211.
Scheme 59: Synthesis of 3-[4-(1-piperidinoethoxy)phenyl]spiro[indene-1,1’-indan]-5,5’-diol hydrochloride 216.
Scheme 60: Synthesis of 3-arylindan-1-ones 219.
Scheme 61: Synthesis of 2-hydroxy-1-indanones 222.
Scheme 62: Synthesis of the 1-indanone 224 from the THP/MOM protected chalcone epoxide 223.
Scheme 63: Synthesis of 1-indanones 227 from γ,δ-epoxy ketones 226.
Scheme 64: Synthesis of 2-hydroxy-2-methylindanone (230).
Scheme 65: Synthesis of 1-indanone derivatives 234 from cyclopropanol derivatives 233.
Scheme 66: Synthesis of substituted 1-indanone derivatives 237.
Scheme 67: Synthesis of 7-methyl substituted 1-indanone 241 from 1,3-pentadiene (238) and 2-cyclopentenone (239...
Scheme 68: Synthesis of disubstituted 1-indanone 246 from the siloxydiene 244 and 2-cyclopentenone 239.
Scheme 69: Synthesis of 5-hydroxy-1-indanone (250) via the Diels–Alder reaction of 1,3-diene 248 with sulfoxid...
Scheme 70: Synthesis of halogenated 1-indanones 253a and 253b.
Scheme 71: Synthesis of 1-indanones 257 and 258 from 2-bromocyclopentenones 254.
Scheme 72: Synthesis of 1-indanone 261 from 2-bromo-4-acetoxy-2-cyclopenten-1-one (260) and 1,2-dihydro-4-viny...
Scheme 73: Synthesis of 1-indanone 265 from 1,2-dihydro-7-methoxy-4-vinylnaphthalene (262) and bromo-substitut...
Scheme 74: Synthesis of 1-indanone 268 from dihydro-3-vinylphenanthrene 266 and 4-acetoxy-2-cyclopenten-1-one (...
Scheme 75: Synthesis of 1-indanone 271 from phenylselenyl-substituted cyclopentenone 268.
Scheme 76: Synthesis of 1-indanone 272 from the trienone 270.
Scheme 77: Synthesis of the 1-indanone 276 from the aldehyde 273.
Scheme 78: Synthesis of 1-indanones 278 and 279.
Scheme 79: Synthesis of 1-indanone 285 from octa-1,7-diyne (282) and cyclopentenone 239.
Scheme 80: Synthesis of benz[f]indan-1-one (287) from cyclopentenone 239 and o-bis(dibromomethyl)benzene (286)....
Scheme 81: Synthesis of 3-methyl-substituted benz[f]indan-1-one 291 from o-bis(dibromomethyl)benzene (286) and...
Scheme 82: Synthesis of benz[f]indan-1-one (295) from the anthracene epidioxide 292.
Scheme 83: Synthesis of 1-indanone 299 from homophthalic anhydride 298 and cyclopentynone 297.
Scheme 84: Synthesis of cyano-substituted 1-indanone derivative 301 from 2-cyanomethylbenzaldehyde (300) and c...
Scheme 85: Synthesis of 1-indanone derivatives 303–305 from ketene dithioacetals 302.
Scheme 86: Synthesis of 1-indanones 309–316.
Scheme 87: Mechanism of the hexadehydro-Diels–Alder (HDDA) reaction.
Scheme 88: Synthesis of 1-indenone 318 and 1-indanones 320 and 321 from tetraynes 317 and 319.
Scheme 89: Synthesis of 1-indanone 320 from the triyn 319.
Scheme 90: Synthesis 1-indanone 328 from 2-methylfuran 324.
Scheme 91: Synthesis of 1-indanones 330 and 331 from furans 329.
Scheme 92: Synthesis of 1-indanone 333 from the cycloadduct 332.
Scheme 93: Synthesis of (S)-3-arylindan-1-ones 335.
Scheme 94: Synthesis of (R)-2-acetoxy-1-indanone 338.
Figure 6: Chemical structures of obtained cyclopenta[α]phenanthrenes 339.
Scheme 95: Synthesis of the benzoindanone 343 from arylacetaldehyde 340 with 1-trimethylsilyloxycyclopentene (...
The reductive decyanation reaction: an overview and recent developments
- Jean-Marc R. Mattalia
Beilstein J. Org. Chem. 2017, 13, 267–284, doi:10.3762/bjoc.13.30
- -withdrawing group. Synthesis of (±)-isoretronecanol 19. DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene [74]. Proposed mechanism with 14a for the NaBH4 induced decyanation reaction (“BH3” = BH3·THF) [74]. Reductive decyanation by a sodium hydride–iodide composite (26 examples) [81]. Proposed mechanism for the
Graphical Abstract
Scheme 1: Mechanism for the reduction under metal dissolving conditions.
Scheme 2: Example of decyanation in metal dissolving conditions coupled with deprotection [30]. TBDMS = tert-buty...
Scheme 3: Preparation of α,ω-dienes [18,33].
Scheme 4: Cyclization reaction using a radical probe [18].
Scheme 5: Synthesis of (±)-xanthorrhizol (8) [39].
Scheme 6: Mechanism for the reduction of α-aminonitriles by hydride donors.
Scheme 7: Synthesis of phenanthroindolizidines and phenanthroquinolizidines [71].
Scheme 8: Two-step synthesis of 5-unsubstituted pyrrolidines (25 examples and 1 synthetic application, see be...
Scheme 9: Synthesis of (±)-isoretronecanol 19. DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene [74].
Scheme 10: Proposed mechanism with 14a for the NaBH4 induced decyanation reaction (“BH3” = BH3·THF) [74].
Scheme 11: Reductive decyanation by a sodium hydride–iodide composite (26 examples) [81].
Scheme 12: Proposed mechanism for the reduction by NaH [81].
Scheme 13: Reductive decyanation catalyzed by nickel nanoparticles. Yields are given in weight % from GC–MS da...
Scheme 14: Decyanation of 2-cyanobenzo[b]thiophene [87].
Scheme 15: Simplified pathways involved in transition-metal-promoted reductive decyanations [93,95].
Scheme 16: Fe-catalyzed reductive decyanation. Numbers in square brackets represent turnover numbers. The TONs...
Scheme 17: Rh-catalyzed reductive decyanation of aryl nitriles (18 examples, 2 synthetic applications) [103].
Scheme 18: Rh-catalyzed reductive decyanation of aliphatic nitriles (15 examples, one synthetic application) [103].
Scheme 19: Ni-catalyzed reductive decyanation (method A: 28 examples and 2 synthetic applications; method B: 3...
Scheme 20: Reductive decyanation catalyzed by the nickel complex 58 (method A, 14 examples, yield ≥ 20% and 1 ...
Scheme 21: Proposed catalytic cycle for the nickel complex 58 catalyzed decyanation (method A). Only the cycle...
Scheme 22: Synthesis of bicyclic lactones [119,120].
Scheme 23: Reductive decyanation of malononitriles and cyanoacetates using NHC-boryl radicals (9 examples). Fo...
Scheme 24: Proposed mechanism for the reduction by NHC-boryl radicals. The other possible pathway (addition of ...
Scheme 25: Structures of organic electron-donors. Only the major Z isomer of 80 is shown [125,127].
Scheme 26: Reductive decyanation of malononitriles and cyanoacetates using organic electron-donors (method A, ...
Scheme 27: Photoreaction of dibenzylmalononitrile with 81 [128].
Scheme 28: Examples of decyanation promoted in acid or basic media [129,131,134,135].
Scheme 29: Mechanism proposed for the base-induced reductive decyanation of diphenylacetonitriles [136].
Scheme 30: Reductive decyanation of triarylacetonitriles [140].
Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state
- Jonas Becher,
- Daria V. Berdnikova,
- Darinka Dzubiel,
- Heiko Ihmels and
- Phil M. Pithan
Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23
- absorption band with two local maxima at 381 nm and 400 nm (MeOH) or 379 nm and 398 nm (MeCN) remains. In contrast, the addition of DBU as a base resulted in the strong increase of the broad absorption band at 431 nm in MeOH and at 457 nm in MeCN. The emission spectrum of 2 in MeOH consists of one intense
- band at 457 nm upon excitation at 400 nm, along with a very weak red-shifted signal at 600 nm. Upon addition of DBU, the emission is efficiently quenched. The red-shifted emission band, however, develops into a very intense signal on addition of the base to the expense of the blue-shifted band. In MeCN
- : after addition of DBU. Normalized emission spectra of 2 (c = 10 µM) in MeOH (A, λex = 400 nm) and MeCN (B, λex = 398 nm). Black lines: without additive, red: after addition of CF3COOH, blue: after addition of DBU. Photometric titration of CB[7] (c = 0.45 mM) to 2 (c = 15 µM) in BPE buffer (with 10% v/v
Graphical Abstract
Figure 1: Structures of quinolizinium derivatives 1a–c and 2.
Scheme 1: Synthesis of 3-hydroxynaphtho[1,2-b]quinolizinium bromide (2).
Figure 2: Absorption (A, c = 100 µM) and normalized emission spectra (B, c = 10 µM or Abs. = 0.1 at λex) of d...
Figure 3: Photometric (A) and fluorimetric (B) acid–base titration (λex = 380 nm) of naphthoquinolizinium 2 (c...
Figure 4: Absorption spectra of 2 (c = 100 µM) in MeOH (A) and MeCN (B). Black lines: without additive, red: ...
Figure 5: Normalized emission spectra of 2 (c = 10 µM) in MeOH (A, λex = 400 nm) and MeCN (B, λex = 398 nm). ...
Figure 6: Photometric titration of CB[7] (c = 0.45 mM) to 2 (c = 15 µM) in BPE buffer (with 10% v/v DMSO) at ...
Figure 7: Photometric (A) and fluorimetric (B) acid–base titration (λex = 380 nm) of 2 (c = 15 µM) in the pre...
Scheme 2: Acid–base equilibrium of hydroxynaphthoquinolizinium 2.
Figure 8: Structures of quinolizinium derivatives 6–8.
Total synthesis of a Streptococcus pneumoniae serotype 12F CPS repeating unit hexasaccharide
- Peter H. Seeberger,
- Claney L. Pereira and
- Subramanian Govindan
Beilstein J. Org. Chem. 2017, 13, 164–173, doi:10.3762/bjoc.13.19
- glycosylating agent by removal of the anomeric TBDPS silyl ether using HF-pyridine and subsequent treatment with trichloroacetonitrile in the presence of catalytic amounts of DBU to afford glycosyl trichloroacetimidate trisaccharide 2 (Scheme 1). With trisaccharide fragments 2 and 3 in hand, the convergent [3
- % over two steps; (d) (PhSe)2, BAIB, NaN3, CH2Cl2, rt, 24 h; (e) NIS, THF/H2O (1:1), rt, 80% over two steps; (f) CCl3CN, DBU, CH2Cl2, 0 °C to rt, 2 h, 72%; (g) TES, TFA, CH2Cl2, 0 °C, 6 h; (h) benzoyl chloride, pyridine, rt, 18 h, 80% over two steps. Synthesis of the non-reducing end trisaccharide 2
- . Reagents and conditions: (a) TMSOTf, CH2Cl2, −30 °C, 74%; (b) NaOMe (0.5 M in MeOH), MeOH, rt; (c) trimethyl orthoacetate, p-TsOH, toluene; (d) 80% AcOH, rt, 71% over three steps; (e) 9, NIS, TMSOTf, dioxane/toluene (3:1), −10 °C, 54%; (f) HF-pyridine, THF, 0 °C; (g) CCl3CN, DBU, CH2Cl2, 0 °C, 57% over two
Graphical Abstract
Figure 1: Structure of the S. pneumoniae serotype 12F capsular polysaccharide repeating unit [15].
Scheme 1: Retrosynthetic analyses of the S. pneumoniae hexasaccharide 1.
Scheme 2: Attempted synthesis of mannosazide building block 15. Reagents and conditions: (a) levulinic acid, ...
Scheme 3: Synthesis of mannosazide building block 18. Reagents and conditions: (a) TBSCl, imidazole, DCM, 0 °...
Scheme 4: Synthesis of the reducing-end trisaccharide 3. Reagents and conditions: (a) TMSOTf, (CH3CH2)2O/CH2Cl...
Scheme 5: Synthesis of monosaccharide building blocks 8, 9 and 26. Reagents and conditions: (a) acetic anhydr...
Scheme 6: Synthesis of the non-reducing end trisaccharide 2. Reagents and conditions: (a) TMSOTf, CH2Cl2, −30...
Scheme 7: Attempted synthesis of hexasaccharide repeating unit 36 via a convergent [3 + 3] glycosylation stra...
Scheme 8: Linear assembly of fully protected hexasaccharide 51. Reagents and conditions: (a) DDQ, CH2Cl2/MeOH...
Scheme 9: Global deprotection to furnish S. pneumonia serotype 12F repeating unit hexasaccharide 1. Reagents ...
The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction
- Erika Bálint,
- Ádám Tajti,
- Anna Ádám,
- István Csontos,
- Konstantin Karaghiosoff,
- Mátyás Czugler,
- Péter Ábrányi-Balogh and
- György Keglevich
Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10
- use of many types of catalysts, such as acids (HCOOH) [15] or bases (NaOH [16], 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) [17], tetramethylguanidine (TMG) [18][19]), p-toluenesulfonyl chloride [20], metal salts (MgSO4) [21], CdI2 [22]), metal complexes (BF3·EtO2 [23][24], t-PcAlCl [15]), and phase
Graphical Abstract
Scheme 1: Synthesis of starting N-benzylideneamines 1.
Scheme 2: Addition of diethyl phosphite to N-benzylidene(butyl)amine in acetonitrile.
Figure 1: IR spectra of the reaction components in acetonitrile solution.
Figure 2: A segment of the time-dependent IR spectrum for the addition of diethyl phosphite to N-benzylidene(...
Figure 3: Concentration profiles of the reaction components in the addition reaction at 80 °C in acetonitrile....
Figure 4: Atomic numbering with anisotropic displacements plot of 5b at −100 °C.
Figure 5: Atomic numbering with anisotropic displacements plot of 5d at −100 °C.
Figure 6: The energy diagram for the reaction with dimethyl phosphite.
Figure 7: The energy diagram for the reaction with diphenylphosphine oxide.
Supramolecular frameworks based on [60]fullerene hexakisadducts
- Andreas Kraft,
- Johannes Stangl,
- Ana-Maria Krause,
- Klaus Müller-Buschbaum and
- Florian Beuerle
Beilstein J. Org. Chem. 2017, 13, 1–9, doi:10.3762/bjoc.13.1
- detector using Cu Kα radiation (unsplit Kα1 + Kα2 doublet, mean wavelength λ = 154.19pm), reflection and transmission geometry. Hexakisadduct 2: C60 (565 mg, 785 µmol, 1 equiv), malonate 1 (3.10 g, 7.84 mmol, 10 equiv) and CBr4 (26.0 g, 78.4 mmol, 100 equiv) were dissolved in dry toluene (500 mL). DBU
Graphical Abstract
Figure 1: Icosahedral arrangement of functional addends for [60]fullerene hexakisadducts with dodecaacids C2 ...
Figure 2: a) Small cavities within the octahedral sites of HFF-1 filled with one CH2Cl2 molecule [57]; b) isolate...
Scheme 1: Synthesis of [60]fullerene dodecaacid C4.
Figure 3: Face centered cubic arrangement of [60]fullerene dodecaacids for frameworks a) HFF-1 [57], b) HFF-2 and...
Figure 4: Hydrogen bonding network for HFF-3 (left, hydrogen bonds yellow) and porous channels along the c ax...
Figure 5: Interpenetration of two distinct hydrogen bonding networks for HFF-3: a) side view indicating the s...
New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation
- Pavel Nagorny and
- Zhankui Sun
Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283
- with DBU and initiator (Ph2CHOH) to accomplish C=O activation and to promote the polymerization reactions (Scheme 6). Highly charged tetraalkylbisammonium salts (i.e., DABCO-Me2·2X) were found to be particularly active catalysts. Based on computational studies, the authors proposed that substrate
Graphical Abstract
Figure 1: Electrophile Activation by Hydrogen Bond Donors [1-16].
Figure 2: Early examples of C–H hydrogen bonds and their recent use in supramolecular chemistry [18,19,32-34].
Scheme 1: Design of 1,2,3-triazole-based catalysts for trityl group transfer through chloride anion binding b...
Scheme 2: Examples of chiral triazole-based catalysts for anion activation designed by Mancheno and co-worker...
Scheme 3: Application of chiral triazole-based catalysts L3 and L4 for counterion activation of pyridinium, q...
Scheme 4: Ammonium salt anion binding via C–H hydrogen bonds in solid state [40-45,50,51].
Scheme 5: Early examples of ammonium salts being used for electrophilic activation of imines in aza-Diels–Ald...
Scheme 6: Ammonium salts as hydrogen bond-donor catalysts by Bibal and co-workers [53,54].
Scheme 7: Tetraalkylammonium catalyst (L6)-catalyzed dearomatization of isoquinolinium salts [50].
Scheme 8: Tetraalkylammonium catalyst L6 complexation to halogen-containing substrates [51].
Scheme 9: Tetraalkylammonium-catalyzed aza-Diels–Alder reaction by Maruoka and co-workers [52].
Scheme 10: (A) Alkylpyridinium catalysts L13-catalyzed reaction of 1-isochroman and silyl ketene acetals by Be...
Scheme 11: Mixed N–H/C–H two hydrogen bond donors L14 and L15 as organocatalysts for ROP of lactide by Bibal a...
Scheme 12: Examples of stable complexes based on halogen bonding [68,69].
Scheme 13: Interaction between (−)-sparteine hydrobromide and (S)-1,2-dibromohexafluoropropane in the cocrysta...
Scheme 14: Iodine-catalyzed reactions that are computationally proposed to proceed through halogen bond to car...
Scheme 15: Transfer hydrogenation of phenylquinolines catalyzed by haloperfluoroalkanes by Bolm and co-workers ...
Scheme 16: Halogen bond activation of benzhydryl bromides by Huber and co-workers [82].
Scheme 17: Halogen bond-donor-catalyzed addition to oxocarbenium ions by Huber and co-workers [89].
Scheme 18: Halogen bond-donor activation of α,β-unsaturated carbonyl compounds in the [2 + 4] cycloaddition re...
Scheme 19: Halogen bond donor activation of imines in the [2 + 4] cycloaddition reaction of imine and Danishef...
Scheme 20: Transfer hydrogenation catalyzed by a chiral halogen bond donor by Tan and co-workers [91].
Scheme 21: Allylation of benzylic alcohols by Takemoto and co-workers [92].
Scheme 22: NIS induced semipinacol rearrangement via C–X bond cleavage [93].
Electron-transfer-initiated benzoin- and Stetter-like reactions in packed-bed reactors for process intensification
- Anna Zaghi,
- Daniele Ragno,
- Graziano Di Carmine,
- Carmela De Risi,
- Olga Bortolini,
- Pier Paolo Giovannini,
- Giancarlo Fantin and
- Alessandro Massi
Beilstein J. Org. Chem. 2016, 12, 2719–2730, doi:10.3762/bjoc.12.268
- 1a with 2-chlorobenzaldehyde 2a furnishing the benzoylated benzoin 3aa (double aroylation product) was selected as the benchmark (Table 1). Quite surprisingly, the polystyrene-supported 1,8-diazabicyclo [5.4.0]undec-7-ene 4 (PS-DBU) was completely inefficient (DMF, 35 °C, Ar atmosphere) in both
Graphical Abstract
Figure 1: Electron-transfer initiated activation of α-diketones (background) and present study.
Scheme 1: Proposed dianionic pathway for the cross-benzoin-like reaction of benzils 1 with aldehydes 2 under ...
Scheme 2: Trapping experiment.
Figure 2: Conversion of the 1a/2a coupling in microreactor R5 operated for 150 h at 50 °C.
Development of a continuous process for α-thio-β-chloroacrylamide synthesis with enhanced control of a cascade transformation
- Olga C. Dennehy,
- Valérie M. Y. Cacheux,
- Benjamin J. Deadman,
- Denis Lynch,
- Stuart G. Collins,
- Humphrey A. Moynihan and
- Anita R. Maguire
Beilstein J. Org. Chem. 2016, 12, 2511–2522, doi:10.3762/bjoc.12.246
- . Elevating the temperature to 90 °C and employing DBU, as a more basic alternative to triethylamine, did not increase the reactivity. Hence, the focus was instead directed on converting the existing batch process (Scheme 2), with sodium ethoxide as base, into a stand-alone continuous process. Initially
Graphical Abstract
Scheme 1: Reaction pathways of α-thio-β-chloroacrylamides.
Scheme 2: Typical three-step batch preparation of α-thio-β-chloroacrylamide.
Scheme 3: Batch process for preparation of α-chloroamide 1.
Scheme 4: Process for the conversion of 2-chloropropionyl chloride and p-toluidine to α-chloroamide 1 under o...
Scheme 5: Conversion of 1 to 2 in continuous mode using MeOH as solvent.
Scheme 6: Optimized process for the conversion of α-chloroamide 1 to α-thioamide 2 under flow conditions.
Scheme 7: Mechanism of the β-chloroacrylamide cascade process [29].
Scheme 8: Optimized flow process for conversion of α-thioamide 2 to α-thio-β-chloroacrylamide Z-3.
Sydnone C-4 heteroarylation with an indolizine ring via Chichibabin indolizine synthesis
- Florin Albota,
- Mino R. Caira,
- Constantin Draghici,
- Florea Dumitrascu and
- Denisa E. Dumitrescu
Beilstein J. Org. Chem. 2016, 12, 2503–2510, doi:10.3762/bjoc.12.245
- followed by solvent extraction gave the sydnone-indolizines 9 in yields of over 50%. If the dissolution of the quaternary salts was incomplete, a small quantity of ethanol could be added. Alternatively, replacement of sodium bicarbonate with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and the use of
- acetonitrile as solvent gave, in the case of the representative pyridinium bromide 8a, compound 9a in 53% yield. Similarly, 9a could be prepared in 54% yield by heating pyridine 6a under reflux with sydnone derivative 7 for four hours followed by the addition of DBU for cyclization. Although all three
Graphical Abstract
Figure 1: Sydnone-pyrroloazines hybrids 1, indolizine (2), sydnone 3, indolizines attached directly to C-4 of...
Scheme 1: Synthesis of pyridinium bromides 8 and sydnone-indolizine hybrids 9 through the Chichibabin reactio...
Figure 2: The molecular structure of 9d with thermal ellipsoids drawn at the 50% probability level. (a) Inver...
Figure 3: Centrosymmetric C–H···O hydrogen bonded dimeric motif in the crystal of 9d.
Scheme 2: The synthesis and mechanism of formation of sydnone-indolizines 12.
Figure 4: Molecular structure of 12c with atoms represented as thermal ellipsoids at the 50% probability leve...
Figure 5: Intramolecular distortion in 12c.
Inhibition of peptide aggregation by means of enzymatic phosphorylation
- Kristin Folmert,
- Malgorzata Broncel,
- Hans v. Berlepsch,
- Christopher H. Ullrich,
- Mary-Ann Siegert and
- Beate Koksch
Beilstein J. Org. Chem. 2016, 12, 2462–2470, doi:10.3762/bjoc.12.240
- ) with respect to the resin and two hour double couplings. A mixture of DBU (1,8-diazabicyclo[5,4,0]undec-7-ene) and piperidine (2% each) in DMF was used for Fmoc-deprotection (3 × 10 min). The resin was washed between each step with DMF and DCM (3 × 6 mL each). Peptides were cleaved from the resin by
Graphical Abstract
Scheme 1: Helical wheel projection of two parallel helical strands and primary structure of KFM6. The recogni...
Figure 1: a) Time-dependent CD spectra and b) corresponding CD-minimum plot for random coil (black) and β-she...
Figure 2: ThT-binding assay of of 15 µM KFM6 in 50 mM Tris/HCl buffer with 10 mM MgCl2 at pH 7.5, 24 °C, and ...
Figure 3: a) TEM micrograph of 15 µM KFM6 in 50 mM Tris/HCl buffer with 10 mM MgCl2 at pH 7.5 and 24 °C. The ...
Figure 4: a) Enzymatic phosphorylation of 15 µM KFM6 in time-dependent CD-minimum plots. Addition of both 200...
Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route
- Felicia D’Andrea,
- Giorgio Catelani,
- Lorenzo Guazzelli and
- Venerando Pistarà
Beilstein J. Org. Chem. 2016, 12, 2343–2350, doi:10.3762/bjoc.12.227
- condensation reactions were performed at room temperature by treating aldohexos-5-ulose derivatives with catalytic amounts of DBU (0.15 equiv) as an organic base promoting agent in toluene, a 1:1 mixture of toluene–CH2Cl2, or CH2Cl2 to circumvent solubility problems (Table 1, see Supporting Information File 1
Graphical Abstract
Figure 1: Stereoisomeric inositols.
Scheme 1: Retrosynthetic approach to inositols from aldohexos-5-uloses.
Figure 2: Hypothesis of the preferred transition state.
Figure 3: Stereoselective reduction of inosose intermediate.
Scheme 2: Intramolecular cyclization of an orthogonally protected L-lyxo-aldohexos-5-ulose derivative.
High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension
- Paul B. Geraghty,
- Calvin Lee,
- Jegadesan Subbiah,
- Wallace W. H. Wong,
- James L. Banal,
- Mohammed A. Jameel,
- Trevor A. Smith and
- David J. Jones
Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223
- 11b, cat. Pd2dba3·4t-Bu3P[HBF4], THF, K3PO4 (2M), 80 °C, 16 h, and ii) N-hexylrhodanine (10 equiv), CHCl3, cat DBU. Extracted UV–vis absorption peak positions for the BXxR series. (λmax in bold). Extracted fluorescence emission peak positions for the BXxR materials (λexcit 580 nm). Extracted UV–vis
Graphical Abstract
Figure 1: Chemical structures of molecular materials with the following variations; BTxR, alkyl side chains o...
Scheme 1: Synthesis of the key intermediates TMS-Tx-BPin (3), i) diisopropylamine (DIA), THF, n-BuLi, −78 °C ...
Scheme 2: Oligothiophenes 4–11 synthesised through reaction of the commercially available 5-bromo-2-thiophene...
Scheme 3: Synthesis of the bithiophene through palladium catalyzed direct arylation, a) i) Pd(OAc)2, PCy3, Pi...
Scheme 4: Synthesis of the key bis-borylated BDT core 13, i) 1.5 equiv B2Pin2, 0.025 equiv [Ir(COD)OMe]2, 0.0...
Scheme 5: Synthesis of the BXR and BTXR series of materials, i) 5-bromothiophene carboxaldehyde, 5b, 7a–c, 9b...
Figure 2: BQR thermal and POM properties. a) DSC thermogram of BQR under nitrogen at a ramp rate of 10 °C min...
Figure 3: BT4R thermal and POM images. a) DSC thermogram of BT4R under nitrogen at a ramp rate of 10 °C min−1...
Figure 4: UV–vis absorption spectra of the BXXR series in CHCl3. An expansion of the peak area is shown in th...
Figure 5: Normalised thin film UV–vis absorption profiles for the BXxR series for, a) as-cast films (from CDCl...
Figure 6: Normalised thin film UV–vis absorption profiles for a) BBR, b) BTR and c) BQR showing as-cast (blac...
Figure 7: Normalised thin film fluorescence emission profiles for BXxR series after excitation at 580 nm, a) ...
Figure 8: Variable temperature thin film UV–vis absorption profiles for BQR, collected using the transmission...
Figure 9: Variable temperature thin-film fluorescence emission profiles for BQR, a) heating and b) cooling, c...
Figure 10: BQR thin film UV–vis (solid lines) and fluorescence emission spectra (dashed lines) collected at rt...
Figure 11: Optimized geometry and molecular orbital surfaces of HOMO (bottom) and LUMO (top) for the BXR serie...
Figure 12: J–V characteristics of BXR:PC71BM BHJ solar cells. (a) device structure, (b) J–V curves for as-cast...
Figure 13: J–V characteristics of BTxR:PC71BM ternary BHJ solar cells, a) device architecture, and b) J–V curv...
Figure 14: J–V characteristics of PTB7-Th:BQR:PC71BM ternary BHJ solar cells. (a) PTB7-Th chemical structure, ...
Isosorbide and dimethyl carbonate: a green match
- Fabio Aricò and
- Pietro Tundo
Beilstein J. Org. Chem. 2016, 12, 2256–2266, doi:10.3762/bjoc.12.218
- , several alternative catalysts and bases have been taken into consideration. Recently it has been reported that 1,5-diazabiciclo(5.4.0)undec-5-ene (DBU) can be used in stoichiometric amounts for the efficient synthesis of isosorbide via DMC chemistry (entry 4, Table 2) [66]. Under these reaction conditions
- , isosorbide was obtained in pure form by filtration on a silica pad and evaporation of the DMC. Even when the amount of DBU was reduced to 5 mol % (entries 4–6, Table 2) the cyclic sugar was still formed in quantitative yield. It is also noteworthy that, although the catalyst employed is homogenous, the
- amount of DBU used was, in the latter case (entry 6, Table 2) only 2.5 mol % for each tetrahydrofuranic cycle. The same synthetic approach can be also employed for the cyclisation of D-mannitol. The synthesis of isosorbide via DMC chemistry takes advantage of the enhanced reactivity of DMC in the
Graphical Abstract
Figure 1: The DOE “Top 10” report [2].
Figure 2: Chemical structure of isosorbide and its epimers isomannide and isoidide.
Scheme 1: Conversion of D-sorbitol to isosorbide via twofold dehydration reaction.
Scheme 2: Possible reaction mechanism for the conversion of D-sorbitol to isosorbide.
Scheme 3: Methoxycarbonylation of isosorbide via DMC chemistry.
Scheme 4: Isosorbide homo- and co-polycarbonate via melt polycondensation.
Scheme 5: Synthesis of DMI via DMC chemistry.
Scheme 6: Comparison of the reactivity of isosorbide with other secondary alcohols in methylation reaction. R...
Figure 3: Chemical structure of isosorbide and its epimers isomannide and isoidide.
The direct oxidative diene cyclization and related reactions in natural product synthesis
- Juliane Adrian,
- Leona J. Gross and
- Christian B. W. Stark
Beilstein J. Org. Chem. 2016, 12, 2104–2123, doi:10.3762/bjoc.12.200
- Industrie (FCI). In addition, individual fellowships by the Ernst-Schering-Stiftung, the Dierks-von-Zweck-Stiftung and the Deutsche Bundesstiftung Umwelt (DBU) are gratefully acknowledged.
Graphical Abstract
Scheme 1: Putative structures of geraniol 1a (R = H) or 1b (R = H) (in 1924), their expected dihydroxylation ...
Scheme 2: Correlation between the substrate double bond geometry and relative stereochemistry of the correspo...
Scheme 3: Mechanisms and classification for the metal-mediated oxidative cyclizations to form 2,5-disubstitut...
Scheme 4: Synthesis of (+)-anhydro-D-glucitol and (+)-D-chitaric acid using an OsO4-mediated oxidative cycliz...
Scheme 5: Total synthesis of neodysiherbaine A via a Ru(VIII)- and an Os(VI)-catalyzed oxidative cyclization,...
Scheme 6: Formal synthesis of ionomycin by Kocienski and co-workers.
Scheme 7: Total synthesis of amphidinolide F by Fürstner and co-workers.
Scheme 8: Brown`s and Donohoe`s oxidative cyclization approach to cis-solamin A.
Scheme 9: Total synthesis of cis-solamin A using a Ru(VIII)-catalyzed oxidative cyclization and enzymatic des...
Scheme 10: Donohoe´s double oxidative cyclization approach to cis-sylvaticin.
Scheme 11: Permanganate-mediated approach to cis-sylvaticin by Brown and co-workers.
Scheme 12: Total synthesis of membranacin using a KMnO4-mediated oxidative cyclization.
Scheme 13: Total synthesis of membrarollin and its analogue 21,22-diepi-membrarollin.
Scheme 14: Total synthesis of rollidecin C and D using a late stage Re(VII)-catalyzed oxidative polycyclizatio...
Scheme 15: Co(II)-catalyzed oxidative cyclization in the total synthesis of asimilobin and gigantetrocin A.
Scheme 16: Mn(VII)-catalyzed oxidative cyclization of a 1,5-diene in the synthesis of trans-(+)-linalool oxide....
Scheme 17: Re(VII)-catalyzed oxidative cyclization in the total synthesis of teurilene.
Scheme 18: Total synthesis of (+)-eurylene via Re(VII)- and Cr(VI)-mediated oxidative cyclizations.
Scheme 19: Synthesis of cis- and trans-THF Rings of eurylene via Mn(VII)-mediated oxidative cyclizations.
Scheme 20: Cr(VI)-catalyzed oxidative cyclization in the total synthesis of venustatriol by Corey et al.
Scheme 21: Ru(VIII)-catalyzed oxidative cyclization of a 1,5-diene in the synthesis and evaluation of its ster...
Scheme 22: Ru(VII)-catalyzed oxidative cyclization of a 5,6-dihydroxy alkene in the synthesis of the core stru...
p-Nitrophenyl carbonate promoted ring-opening reactions of DBU and DBN affording lactam carbamates
- Madhuri Vangala and
- Ganesh P Shinde
Beilstein J. Org. Chem. 2016, 12, 2086–2092, doi:10.3762/bjoc.12.197
- Madhuri Vangala Ganesh P Shinde Department of Chemistry, Indian Institute of Science Education and Research, Pune 411 008, India 10.3762/bjoc.12.197 Abstract The amidine bases DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) display nucleophilic behaviour
- with a large substrate scope. Keywords: carbonates; DBN; DBU; lactams; p-nitrophenyl; Introduction Among various organic bases, amidines such as DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and DBN (1,5-diazabicyclo[4.3.0]non-5-ene) having an imino group attached to the α-carbon of the amine are
- synthetically useful and strong neutral bases. Besides, DBU and DBN catalyze various organic reactions such as dehydrohalogenations [1], carbonylations [2], amidations [3] and Baylis–Hillman reactions [4]. These bicyclic amidines have been thought to be non-nucleophilic bases, but meanwhile numerous examples
Graphical Abstract
Scheme 1: Reaction of DBU with p-nitrophenyl carbonate.
Scheme 2: Reaction of DBN with p-nitrophenyl carbonates.
Scope and limitations of a DMF bio-alternative within Sonogashira cross-coupling and Cacchi-type annulation
- Kirsty L. Wilson,
- Alan R. Kennedy,
- Jane Murray,
- Ben Greatrex,
- Craig Jamieson and
- Allan J. B. Watson
Beilstein J. Org. Chem. 2016, 12, 2005–2011, doi:10.3762/bjoc.12.187
- . Organic bases such as pyridine (Table 2, entry 2), DIPEA (Table 2, entry 4), and Et3N (Table 2, entry 6) were tolerated at 25 °C with DIPEA and Et3N also tolerated at 50 °C. DBU, however, was not tolerated at any temperature (Table 2, entry 8). With the exception of KOAc (Table 2, entry 1), all inorganic
Graphical Abstract
Scheme 1: The Sonogashira reaction.
Figure 1: Cyrene vs. DMF – selected physical properties [31,32].
Figure 2: Aldol products 4a and 4b and single crystal X-ray structure of 4b.
Scheme 2: Cyrene-based Sonogashira cross-coupling: Substrate scope. Isolated yields. aYield using DMF as solv...
Scheme 3: Cacchi-type annulation of o-amino/hydroxy iodoarenes. Isolated yields. aYield using DMF as solvent.
Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates
- Maurizio Selva,
- Alvise Perosa,
- Sandro Guidi and
- Lisa Cattelan
Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181
- therefore operate (Scheme 11) [63]. Munshi et al. also recently investigated the reaction of glycerol and DMC by proposing a novel ionic liquid catalyst based on the reaction of diazabicyclo[5.4.0]undec-7-ene (DBU) with an alcohol ROH and CO2 (Scheme 12) [64]. As best found reaction conditions (only 0.22
- carbonyl moiety (Scheme 14). It must be noted that in these two examples the selectivity of the reaction could be tuned just by changing the catalyst precursor: by switching from the DBU-based IL to the DABCO–DMC IL, the selectivity changed from 82% for glycerol carbonate, to 83% for glycidol. In another
- such systems was found to be higher than that of strong bases including DBU or DABCO. This phenomenon was observed by several authors [64][76] and explained by a cooperative ambiphilic (nucleophilic–electrophilic) activation effect in which the IL anion and cation may activate respectively the
Graphical Abstract
Scheme 1: The transesterification of diethyl oxalate (DEO) with phenol catalyzed by MoO3/SiO2.
Scheme 2: Transesterification of a triglyceride (TG) with DMC for biodiesel production using KOH as the base ...
Scheme 3: Top: Green methylation of phosphines and amines by dimethyl carbonate (Q = N, P). Bottom: anion met...
Figure 1: Structures of some representative SILs and PILs systems. MCF is a silica-based mesostructured mater...
Scheme 4: Synthesis of the acid polymeric IL. EGDMA: ethylene glycol dimethacrylate.
Scheme 5: The transesterification of sec-butyl acetate with MeOH catalyzed by some acidic imidazolium ILs.
Figure 2: Representative examples of ionic liquids for biodiesel production.
Scheme 6: Top: phosgenation of methanol; middle: EniChem and Ube processes; bottom: Asahi process for the pro...
Scheme 7: The transesterification in the synthesis of organic carbonates.
Scheme 8: The transesterification of DMC with alcohols and diols.
Scheme 9: Transesterification of glycerol with DMC in the presence of 1-n-butyl-3-methylimidazolium-2-carboxy...
Scheme 10: Synthesis of the BMIM-2-CO2 catalyst from butylimidazole and DMC.
Scheme 11: Plausible cooperative (nucleophilic–electrophilic) mechanism for the transesterification of glycero...
Scheme 12: Synthesis of diazabicyclo[5.4.0]undec-7-ene-based ionic liquids.
Scheme 13: Synthesis of the DABCO–DMC ionic liquid.
Scheme 14: Cooperative mechanism of ionic liquid-catalyzed glycidol production.
Scheme 15: [TMA][OH]-catalyzed synthesis of glycidol (GD) from glycerol and dimethyl carbonate [46].
Scheme 16: [BMIM]OH-catalyzed synthesis of DPC from DMC and 1-pentanol.
Figure 3: Representative examples of ionic liquids for biodiesel production.
Figure 4: Acyclic non-symmetrical organic carbonates synthetized with 1-(trimethoxysilyl)propyl-3-methylimida...
Scheme 17: A simplified reaction mechanism for DMC production.
Scheme 18: [P8881][MeOCO2] metathesis with acetic acid and phenol.
Figure 5: Examples of carbonates obtained through transesterification using phosphonium salts as catalysts.
Scheme 19: Examples of carbonates obtained from different bio-based diols using [P8881][CH3OCO2] as catalyst.
Scheme 20: Ambiphilic catalysis for transesterification reactions in the presence of carbonate phosphonium sal...
Rearrangements of organic peroxides and related processes
- Ivan A. Yaremenko,
- Vera A. Vil’,
- Dmitry V. Demchuk and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162
- of 2-alkenylcyclopentanones 276 and cyclopentenones 277 [358]. Thus, the treatment of a solution of endoperoxides 275 in CH2Cl2 with triethylamine while increasing the temperature from 0 °C to room temperature affords hydroxyketone 276. The use of the stronger base DBU results in the formation of 2
Graphical Abstract
Figure 1: The named transformations considered in this review.
Scheme 1: The Baeyer–Villiger oxidation.
Scheme 2: The general mechanism of the peracid-promoted Baeyer–Villiger oxidation.
Scheme 3: General mechanism of the Lewis acid-catalyzed Baeyer–Villiger rearrangement.
Scheme 4: The theoretically studied mechanism of the BV oxidation reaction promoted by H2O2 and the Lewis aci...
Scheme 5: Proton movements in the transition states of the Baeyer–Villiger oxidation.
Scheme 6: The dependence of the course of the Baeyer–Villiger oxidation on the type of O–O-bond cleavage in t...
Scheme 7: The acid-catalyzed Baeyer–Villiger oxidation of cyclic epoxy ketones 22.
Scheme 8: Oxidation of isophorone oxide 29.
Scheme 9: Synthesis of acyl phosphate 32 from acyl phosphonate 31.
Scheme 10: Synthesis of aflatoxin B2 (36).
Scheme 11: The Baeyer–Villiger rearrangement of ketones 37 to lactones 38.
Scheme 12: Synthesis of 3,4-dimethoxybenzoic acid (40) via Baeyer–Villiger oxidation.
Scheme 13: Oxone transforms α,β-unsaturated ketones 43 into vinyl acetates 44.
Scheme 14: The Baeyer–Villiger oxidation of ketones 45 using diaryl diselenide and hydrogen peroxide.
Scheme 15: Baeyer–Villiger oxidation of (E)-2-methylenecyclobutanones.
Scheme 16: Oxidation of β-ionone (56) by H2O2/(BnSe)2 with formation of (E)-2-(2,6,6-trimethylcyclohex-1-en-1-...
Scheme 17: The mechanism of oxidation of ketones 58a–f by hydrogen peroxide in the presence of arsonated polys...
Scheme 18: Oxidation of ketone (58b) by H2O2 to 6-methylcaprolactone (59b) catalyzed by Pt complex 66·BF4.
Scheme 19: Oxidation of ketones 67 with H2O2 in the presence of [(dppb}Pt(µ-OH)]22+.
Scheme 20: The mechanism of oxidation of ketones 67 in the presence of [(dppb}Pt(µ-OH)]22+ and H2O2.
Scheme 21: Oxidation of benzaldehydes 69 in the presence of the H2O2/MeReO3 system.
Scheme 22: Oxidation of acetophenones 72 in the presence of the H2O2/MeReO3 system.
Scheme 23: Baeyer–Villiger oxidation of 2-adamantanone (45c) in the presence of Sn-containing mesoporous silic...
Scheme 24: Aerobic Baeyer–Villiger oxidation of ketones 76 using metal-free carbon.
Scheme 25: A regioselective Baeyer-Villiger oxidation of functionalized cyclohexenones 78 into a dihydrooxepin...
Scheme 26: The oxidation of aldehydes and ketones 80 by H2O2 catalyzed by Co4HP2Mo15V3O62.
Scheme 27: The cleavage of ketones 82 with hydrogen peroxide in alkaline solution.
Scheme 28: Oxidation of ketones 85 to esters 86 with H2O2–urea in the presence of KHCO3.
Scheme 29: Mechanism of the asymmetric oxidation of cyclopentane-1,2-dione 87a with the Ti(OiPr)4/(+)DET/t-BuO...
Scheme 30: The oxidation of cis-4-tert-butyl-2-fluorocyclohexanone (93) with m-chloroperbenzoic acid.
Scheme 31: The mechanism of the asymmetric oxidation of 3-substituted cyclobutanone 96a in the presence of chi...
Scheme 32: Enantioselective Baeyer–Villiger oxidation of cyclic ketones 98.
Scheme 33: Regio- and enantioselective Baeyer–Villiger oxidation of cyclic ketones 101.
Scheme 34: The proposed mechanism of the Baeyer–Villiger oxidation of acetal 105f.
Scheme 35: Synthesis of hydroxy-10H-acridin-9-one 117 from tetramethoxyanthracene 114.
Scheme 36: The Baeyer–Villiger oxidation of the fully substituted pyrrole 120.
Scheme 37: The Criegee rearrangement.
Scheme 38: The mechanism of the Criegee reaction of a peracid with a tertiary alcohol 122.
Scheme 39: Criegee rearrangement of decaline ethylperoxoate 127 into ketal 128.
Scheme 40: The ionic cleavage of 2-methoxy-2-propyl perester 129.
Scheme 41: The Criegee rearrangement of α-methoxy hydroperoxide 136.
Scheme 42: Synthesis of enol esters and acetals via the Criegee rearrangement.
Scheme 43: Proposed mechanism of the transformation of 1-hydroperoxy-2-oxabicycloalkanones 147a–d.
Scheme 44: Transformation of 3-hydroxy-1,2-dioxolanes 151 into diketone derivatives 152.
Scheme 45: Criegee rearrangement of peroxide 153 with the mono-, di-, and tri-O-insertion.
Scheme 46: The sequential Criegee rearrangements of adamantanes 157a,b.
Scheme 47: Synthesis of diaryl carbonates 160a–d from triarylmethanols 159a–d through successive oxygen insert...
Scheme 48: The synthesis of sesquiterpenes 162 from ketone 161 with a Criegee rearrangement as one key step.
Scheme 49: Synthesis of trans-hydrindan derivatives 164, 165.
Scheme 50: The Hock rearrangement.
Scheme 51: The general scheme of the cumene process.
Scheme 52: The Hock rearrangement of aliphatic hydroperoxides.
Scheme 53: The mechanism of solvolysis of brosylates 174a–c and spiro cyclopropyl carbinols 175a–c in THF/H2O2....
Scheme 54: The fragmentation mechanism of hydroperoxy acetals 178 to esters 179.
Scheme 55: The acid-catalyzed rearrangement of phenylcyclopentyl hydroperoxide 181.
Scheme 56: The peroxidation of tertiary alcohols in the presence of a catalytic amount of acid.
Scheme 57: The acid-catalyzed reaction of bicyclic secondary alcohols 192 with hydrogen peroxide.
Scheme 58: The photooxidation of 5,6-disubstituted 3,4-dihydro-2H-pyrans 196.
Scheme 59: The oxidation of tertiary alcohols 200a–g, 203a,b, and 206.
Scheme 60: Transformation of functional peroxide 209 leading to 2,3-disubstitued furans 210 in one step.
Scheme 61: The synthesis of carbazoles 213 via peroxide rearrangement.
Scheme 62: The construction of C–N bonds using the Hock rearrangement.
Scheme 63: The synthesis of moiety 218 from 217 which is a structural motif in the antitumor–antibiotic of CC-...
Scheme 64: The in vivo oxidation steps of cholesterol (219) by singlet oxygen.
Scheme 65: The proposed mechanism of the rearrangement of cholesterol-5α-OOH 220.
Scheme 66: Photochemical route to artemisinin via Hock rearrangement of 223.
Scheme 67: The Kornblum–DeLaMare rearrangement.
Scheme 68: Kornblum–DeLaMare transformation of 1-phenylethyl tert-butyl peroxide (225).
Scheme 69: The synthesis 4-hydroxyenones 230 from peroxide 229.
Scheme 70: The Kornblum–DeLaMare rearrangement of peroxide 232.
Scheme 71: The reduction of peroxide 234.
Scheme 72: The Kornblum–DeLaMare rearrangement of endoperoxide 236.
Scheme 73: The rearrangement of peroxide 238 under Kornblum–DeLaMare conditions.
Scheme 74: The proposed mechanism of rearrangement of peroxide 238.
Scheme 75: The Kornblum–DeLaMare rearrangement of peroxides 242a,b.
Scheme 76: The base-catalyzed rearrangements of bicyclic endoperoxides having electron-withdrawing substituent...
Scheme 77: The base-catalyzed rearrangements of bicyclic endoperoxides 249a,b having electron-donating substit...
Scheme 78: The base-catalyzed rearrangements of bridge-head substituted bicyclic endoperoxides 251a,b.
Scheme 79: The Kornblum–DeLaMare rearrangement of hydroperoxide 253.
Scheme 80: Synthesis of β-hydroxy hydroperoxide 254 from endoperoxide 253.
Scheme 81: The amine-catalyzed rearrangement of bicyclic endoperoxide 263.
Scheme 82: The base-catalyzed rearrangement of meso-endoperoxide 268 into 269.
Scheme 83: The photooxidation of 271 and subsequent Kornblum–DeLaMare reaction.
Scheme 84: The Kornblum–DeLaMare rearrangement as one step in the oxidation reaction of enamines.
Scheme 85: The Kornblum–DeLaMare rearrangement of 3,5-dihydro-1,2-dioxenes 284, 1,2-dioxanes 286, and tert-but...
Scheme 86: The Kornblum–DeLaMare rearrangement of epoxy dioxanes 290a–d.
Scheme 87: Rearrangement of prostaglandin H2 292.
Scheme 88: The synthesis of epicoccin G (297).
Scheme 89: The Kornblum–DeLaMare rearrangement used in the synthesis of phomactin A.
Scheme 90: The Kornblum–DeLaMare rearrangement in the synthesis of 3H-quinazolin-4-one 303.
Scheme 91: The Kornblum–DeLaMare rearrangement in the synthesis of dolabriferol (308).
Scheme 92: Sequential transformation of 3-substituted 2-pyridones 309 into 3-hydroxypyridine-2,6-diones 311 in...
Scheme 93: The Kornblum–DeLaMare rearrangement of peroxide 312 into hydroxy enone 313.
Scheme 94: The Kornblum–DeLaMare rearrangement in the synthesis of polyfunctionalized carbonyl compounds 317.
Scheme 95: The Kornblum–DeLaMare rearrangement in the synthesis of (Z)-β-perfluoroalkylenaminones 320.
Scheme 96: The Kornblum–DeLaMare rearrangement in the synthesis of γ-ketoester 322.
Scheme 97: The Kornblum–DeLaMare rearrangement in the synthesis of diterpenoids 326 and 328.
Scheme 98: The synthesis of natural products hainanolidol (331) and harringtonolide (332) from peroxide 329.
Scheme 99: The synthesis of trans-fused butyrolactones 339 and 340.
Scheme 100: The synthesis of leucosceptroid C (343) and leucosceptroid P (344) via the Kornblum–DeLaMare rearra...
Scheme 101: The Dakin oxidation of arylaldehydes or acetophenones.
Scheme 102: The mechanism of the Dakin oxidation.
Scheme 103: A solvent-free Dakin reaction of aromatic aldehydes 356.
Scheme 104: The organocatalytic Dakin oxidation of electron-rich arylaldehydes 358.
Scheme 105: The Dakin oxidation of electron-rich arylaldehydes 361.
Scheme 106: The Dakin oxidation of arylaldehydes 358 in water extract of banana (WEB).
Scheme 107: A one-pot approach towards indolo[2,1-b]quinazolines 364 from indole-3-carbaldehydes 363 through th...
Scheme 108: The synthesis of phenols 367a–c from benzaldehydes 366a-c via acid-catalyzed Dakin oxidation.
Scheme 109: Possible transformation paths of the highly polarized boric acid coordinated H2O2–aldehyde adduct 3...
Scheme 110: The Elbs oxidation of phenols 375 to hydroquinones.
Scheme 111: The mechanism of the Elbs persulfate oxidation of phenols 375 affording p-hydroquinones 376.
Scheme 112: Oxidation of 2-pyridones 380 under Elbs persulfate oxidation conditions.
Scheme 113: Synthesis of 3-hydroxy-4-pyridone (384) via an Elbs oxidation of 4-pyridone (382).
Scheme 114: The Schenck rearrangement.
Scheme 115: The Smith rearrangement.
Scheme 116: Three main pathways of the Schenck rearrangement.
Scheme 117: The isomerization of hydroperoxides 388 and 389.
Scheme 118: Trapping of dioxacyclopentyl radical 392 by oxygen.
Scheme 119: The hypothetical mechanism of the Schenck rearrangement of peroxide 394.
Scheme 120: The autoxidation of oleic acid (397) with the use of labeled isotope 18O2.
Scheme 121: The rearrangement of 18O-labeled hydroperoxide 400 under an atmosphere of 16O2.
Scheme 122: The rearrangement of the oleate-derived allylic hydroperoxides (S)-421 and (R)-425.
Scheme 123: Mechanisms of Schenck and Smith rearrangements.
Scheme 124: The rearrangement and cyclization of 433.
Scheme 125: The Wieland rearrangement.
Scheme 126: The rearrangement of bis(triphenylsilyl) 439 or bis(triphenylgermyl) 441 peroxides.
Scheme 127: The oxidative transformation of cyclic ketones.
Scheme 128: The hydroxylation of cyclohexene (447) in the presence of tungstic acid.
Scheme 129: The oxidation of cyclohexene (447) under the action of hydrogen peroxide.
Scheme 130: The reaction of butenylacetylacetone 455 with hydrogen peroxide.
Scheme 131: The oxidation of bridged 1,2,4,5-tetraoxanes.
Scheme 132: The proposed mechanism for the oxidation of bridged 1,2,4,5-tetraoxanes.
Scheme 133: The rearrangement of ozonides.
Scheme 134: The acid-catalyzed oxidative rearrangement of malondialdehydes 462 under the action of H2O2.
Scheme 135: Pathways of the Lewis acid-catalyzed cleavage of dialkyl peroxides 465 and ozonides 466.
Scheme 136: The mechanism of the transformation of (tert-butyldioxy)cyclohexanedienones 472.
Scheme 137: The synthesis of Vitamin K3 from 472a.
Scheme 138: Proposed mechanism for the transformation of 478d into silylated endoperoxide 479d.
Scheme 139: The rearrangement of hydroperoxide 485 to form diketone 486.
Scheme 140: The base-catalyzed rearrangement of cyclic peroxides 488a–g.
Scheme 141: Synthesis of chiral epoxides and aldols from peroxy hemiketals 491.
Scheme 142: The multistep transformation of (R)-carvone (494) to endoperoxides 496a–e.
Scheme 143: The decomposition of anthracene endoperoxide 499.
Scheme 144: Synthesis of esters 503 from aldehydes 501 via rearrangement of peroxides 502.
Scheme 145: Two possible paths for the base-promoted decomposition of α-azidoperoxides 502.
Scheme 146: The Story decomposition of cyclic diperoxide 506a.
Scheme 147: The Story decomposition of cyclic triperoxide 506b.
Scheme 148: The thermal rearrangement of endoperoxides A into diepoxides B.
Scheme 149: The transformation of peroxide 510 in the synthesis of stemolide (511).
Scheme 150: The possible mechanism of the rearrangement of endoperoxide 261g.
Scheme 151: The photooxidation of indene 517.
Scheme 152: The isomerization of ascaridole (523).
Scheme 153: The isomerization of peroxide 525.
Scheme 154: The thermal transformation of endoperoxide 355.
Scheme 155: The photooxidation of cyclopentadiene (529) at a temperature higher than 0 °C.
Scheme 156: The thermal rearrangement of endoperoxides 538a,b.
Scheme 157: The transformation of peroxides 541.
Scheme 158: The thermal rearrangements of strained cyclic peroxides.
Scheme 159: The thermal rearrangement of diacyl peroxide 551 in the synthesis of C4-epi-lomaiviticin B core 553....
Scheme 160: The 1O2 oxidation of tryptophan (554) and rearrangement of dioxetane intermediate 555.
Scheme 161: The Fe(II)-promoted cleavage of aryl-substituted bicyclic peroxides.
Scheme 162: The proposed mechanism of the Fe(II)-promoted rearrangement of 557a–c.
Scheme 163: The reaction of dioxolane 563 with Fe(II) sulfate.
Scheme 164: Fe(II)-promoted rearrangement of 1,2-dioxane 565.
Scheme 165: Fe(II) cysteinate-promoted rearrangement of 1,2-dioxolane 568.
Scheme 166: The transformation of 1,2-dioxanes 572a–c under the action of FeCl2.
Scheme 167: Fe(II) cysteinate-promoted transformation of tetraoxane 574.
Scheme 168: The CoTPP-catalyzed transformation of bicyclic endoperoxides 600a–d.
Scheme 169: The CoTPP-catalyzed transformation of epoxy-1,2-dioxanes.
Scheme 170: The Ru(II)-catalyzed reactions of 1,4-endoperoxide 261g.
Scheme 171: The Ru(II)-catalyzed transformation as a key step in the synthesis of elyiapyrone A (610) from 1,4-...
Scheme 172: Peroxides with antimalarial activity.
Scheme 173: The interaction of iron ions with artemisinin (616).
Scheme 174: The interaction of FeCl2 with 1,2-dioxanes 623, 624.
Scheme 175: The mechanism of reaction 623 and 624 with Fe(II)Cl2.
Scheme 176: The reaction of bicyclic natural endoperoxides G3-factors 631–633 with FeSO4.
Scheme 177: The transformation of terpene cardamom peroxide 639.
Scheme 178: The different ways of the cleavage of tetraoxane 643.
Scheme 179: The LC–MS analysis of interaction of tetraoxane 646 with iron(II)heme 647.
Scheme 180: The rearrangement of 3,6-epidioxy-1,10-bisaboladiene (EDBD, 649).
Scheme 181: Easily oxidized substrates.
Scheme 182: Biopathway of synthesis of prostaglandins.
Scheme 183: The reduction and rearrangements of isoprostanes.
Scheme 184: The partial mechanism for linoleate 658 oxidation.
Scheme 185: The transformation of lipid hydroperoxide.
Scheme 186: The acid-catalyzed cleavage of the product from free-radical oxidation of cholesterol (667).
Scheme 187: Two pathways of catechols oxidation.
Scheme 188: Criegee-like or Hock-like rearrangement of the intermediate hydroperoxide 675 in dioxygenase enzyme...
Scheme 189: Carotinoides 679 cleavage by carotenoid cleavage dioxygenases.
On the cause of low thermal stability of ethyl halodiazoacetates
- Magnus Mortén,
- Martin Hennum and
- Tore Bonge-Hansen
Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155
- added DBU (1.4 mmol) and stirring was continued at 0 °C for 5 min before the N-halosuccinimide (1.1 mmol, NBS or NCS or NIS) of choice was added. There was an immediate color change from yellow to orange or red, and the conversion of EDA was completed in less than 5 min as judged by TLC analysis. After
Graphical Abstract
Figure 1: Relative stability and nucleophilicity of non-stabilized (R = H, alkyl) diazo compounds (left) and ...
Scheme 1: Synthesis of ethyl halodiazoacetates [11].
Figure 2: a) The decay of 2b in toluene-d8 at 35 °C. b) The plot of log(Δ[2b]) vs time.
Scheme 2: Proposed rate determining step for the thermal decomposition of 2a–c.
Figure 3: Transition-state energies (kcal/mol) for the release of N2 and formation of the singlet carbenes. T...
Figure 4: Thermal stability of 1 and 2a–c, and the α-substituents’ contribution to π-donation.
Figure 5: NBO atomic charges and IR stretching frequencies calculated [21] and experimentally recorded for 1 and ...
Figure 6: NBO atomic charges of the singlet carbenes from 1 and 2a,b, and d.
Figure 7: Relative thermal stability of halodiazoacetates (red color).
Figure 8: Relative nucleophilicity of halodiazoacetates (red color).
Flow carbonylation of sterically hindered ortho-substituted iodoarenes
- Carl J. Mallia,
- Gary C. Walter and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2016, 12, 1503–1511, doi:10.3762/bjoc.12.147
- , did not significantly change the isolated yield of 5. However, changing to the stronger base DBU (pKa in water at 25 °C = 13.5) [40] dramatically reduced the isolated yield (Table 1, entry 8). A wider temperature range was also investigated (Table 1, entries 9–11). This resulted in only a small
Graphical Abstract
Figure 1: Steric interactions of the carbon monoxide coordination to the aryl complex intermediate.
Figure 2: A) molecular structure of complex 1; B) ball and stick representation of X-ray structure; C) ball a...
Figure 3: Reverse “tube-in-tube” reactor.
Scheme 1: Comparison of plug flow reactor carbonylation (left) and “tube-in-tube” reactor carbonylation (righ...
Scheme 2: Schematic diagram of the flow process.
Figure 4: Phosphine ligands used for the ortho-carbonylation reaction.
Scheme 3: The batch carbonylation of 2-chloro-1-iodobenzene in conventional lab (top) and using a Parr autocl...
Scheme 4: Structures of ortho-substituted carboxylic acids prepared via a continuous flow hydroxy-carbonylati...
Scheme 5: Flow carbonylation of 2-iodonaphtalene.
Figure 5: X-ray structure of substrate 33.
Scheme 6: Scale up synthesis of 2-chloro-4-fluorobenzoic acid (20).
