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Search for "rhodium" in Full Text gives 188 result(s) in Beilstein Journal of Organic Chemistry.
Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles
- Franca M. Cordero,
- Carolina Vurchio,
- Stefano Cicchi,
- Armin de Meijere and
- Alberto Brandi
Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39
- )-catalyzed opening of the VCP moiety embedded in an azapolycyclic system occurs at high temperature (110–130 °C) to afford the corresponding 1,3-dienes in moderate yield (34–53%). Keywords: nitrogen heterocycles; rearrangement; rhodium; small ring systems; spiro compounds; Introduction The cyclopropyl
- other interesting transformations, such as the [5 + 2] cycloadditions of vinylcyclopropanes to alkynes developed by Wender and co-workers [36][37]. It is known, that rhodium-catalyzed rearrangements of unactivated VCPs, without any functional substituent, usually afford dienes. In order to evaluate the
- bond to form the intermediates C which can undergo metal hydride elimination or 1,3-hydride migration to the rhodium to give, respectively, the allyl- and alkylrhodium(III) hydride complexes D and F. Metal extrusion by reductive elimination leads to the observed dienes and regeneration of the catalyst
Graphical Abstract
Scheme 1: General approach to spirocyclopropanated tetrahydropyridones by 1,3-dipolar cycloaddition/thermal r...
Scheme 2: Synthesis of tetrahydrospiro[cyclopropane-1,1’(2’H,6’H)-pyrido[2,1-a]isoquinolin]-2’-one 8.
Scheme 3: Synthesis of 7’-oxohexahydro spiro[cyclopropane-1-8’(5’H)indolizines] 12.
Scheme 4: Olefination of spirocyclopropanated heterocyclic ketones 8, 12 and 16.
Figure 1: Key NOE interactions. 18: 11b-H/11-H, 11b-H/6-H, 11b-H/Ht, Hv/2-CH3; E-19: Hb/CH3, Hc/11b-H, Hc/11-...
Scheme 5: Rearrangement of VCPs 15 and 17 catalyzed by Rh(PPh3)3Cl.
Scheme 6: Mechanism of the rearrangement of heterocyclic VCPs catalyzed by Rh(PPh3)3Cl.
Backbone tuning in indenylidene–ruthenium complexes bearing an unsaturated N-heterocyclic carbene
- César A. Urbina-Blanco,
- Xavier Bantreil,
- Hervé Clavier,
- Alexandra M. Z. Slawin and
- Steven P. Nolan
Beilstein J. Org. Chem. 2010, 6, 1120–1126, doi:10.3762/bjoc.6.128
- phosphanes, and more recently, has been used to study the electronic properties of NHCs [34]. However, the high toxicity of [Ni(CO)4] encouraged the search for analogous systems using different metals to determine the TEP. One of the most popular and suitable alternatives to nickel is a rhodium carbonyl
- parameters associated with these synthetic variations. Using a rhodium carbonyl system, the electronic variations brought about by substituents on the NHC lead to the following ligand electronic donor scale: IMesMe > IMes > IMesBr > IMesCl. The size of the substituent also affects the steric hindrance of the
Graphical Abstract
Figure 1: Representative olefin metathesis catalysts.
Figure 2: Highly active olefin metathesis catalysts bearing NHC with backbone substitution.
Scheme 1: Synthesis of the free NHCs.
Scheme 2: Synthesis of [RhCl(CO)2(NHC)] complexes.
Scheme 3: Synthesis of [RuCl2(NHC)(PCy3)(Ind)] complexes.
Recent advances in carbocupration of α-heterosubstituted alkynes
- Ahmad Basheer and
- Ilan Marek
Beilstein J. Org. Chem. 2010, 6, No. 77, doi:10.3762/bjoc.6.77
- adduct 29. However, the reaction was not completely stereoselective (Scheme 13) [25]. Although not a copper-mediated transformation, the rhodium-catalyzed carbozincation of ynamides should be noted since the regioselectivities were, in general, high (>19:1), though in some cases somewhat diminished with
- Me2Zn (5:1) [26][27]. The rhodium-catalyzed annulation of ynamides with arylboron compounds containing an aldehyde or a ketone moiety have also been developed and lead to functionalized 2-amidoindenes with good levels of regioselectivity [28]. P-substituted alkynes Stereo- and regioselective
Graphical Abstract
Scheme 1: General scheme for the carbocupration reaction.
Scheme 2: Regioselectivity in the carbocupration reaction.
Scheme 3: Carbocupration of α-alkoxyalkynes.
Scheme 4: Carbocupration of substituted α-alkoxyalkynes.
Scheme 5: Formation of the branched isomer.
Scheme 6: Formation of the linear isomer.
Scheme 7: Carbocupration of O-alkynyl carbamates.
Scheme 8: Carbocupration of ynamines.
Scheme 9: Carbocupration of ynamide.
Scheme 10: Formation of aldol products possessing stereogenic quaternary carbon centers.
Scheme 11: Carbocupration of alkynyl sulfonamide.
Scheme 12: Tandem carbocupration-sigmatropic rearrangement.
Scheme 13: Silylcupration of alkynyl sulfonamides.
Scheme 14: Carbocupration of P-substituted alkynes.
Scheme 15: Carbocupration of alkynylphosphonates.
Scheme 16: Carbocupration of thioalkynes.
Scheme 17: Tandem carbocupration-1,2-metalate rearrangement.
Scheme 18: Carbocupration with functionalized organocopper species.
Scheme 19: Carbocupration of alkynyl sulfoxides.
Scheme 20: Carbocupration of alkynyl sulfones.
Scheme 21: Carbocupration of alkynyl sulfoximines.
Scheme 22: Carbocupration of alkynylsilanes.
Scheme 23: Carbocupration of functionalized alkynylsilanes.
Scheme 24: Silyl- and stannyl cupration of silyl- and stannylalkynes.
Molecular recognition of organic ammonium ions in solution using synthetic receptors
- Andreas Späth and
- Burkhard König
Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32
Graphical Abstract
Figure 1: Biologically important amines and quaternary ammonium salts: histamine (1), dopamine (2) and acetyl...
Figure 2: Crown ether 18-crown-6.
Figure 3: Conformations of 18-crown-6 (4) in solvents of different polarity.
Figure 4: Binding topologies of the ammonium ion depending on the crown ring size.
Figure 5: A “pseudorotaxane” structure consisting of 24-crown-8 and a secondary ammonium ion (5); R = Ph.
Figure 6: Typical examples of azacrown ethers, cryptands and related aza macrocycles.
Figure 7: Binding of ammonium to azacrown ethers and cryptands [111-113].
Figure 8: A 19-crown-6-ether with decalino blocking groups (11) and a thiazole-dibenzo-18-crown-6-ether (12).
Figure 9: 1,3-Bis(6-oxopyridazin-1-yl)propane derivatives 13 and 14 by Campayo et al.
Figure 10: Fluorescent azacrown-PET-sensors based on coumarin.
Figure 11: Two different pyridino-cryptands (17 and 18) compared to a pyridino-crown (19); chiral ammonium ion...
Figure 12: Pyridino-18-crown-6 ligand (21), a similar acridino-18-crown-6 ligand (22) and a structurally relat...
Figure 13: Ciral pyridine-azacrown ether receptors 24.
Figure 14: Chiral 15-crown-5 receptors 26 and an analogue 18-crown-6 ligand 27 derived from amino alcohols.
Figure 15: C2-symmetric chiral 18-crown-6 amino alcohol derivatives 28 and related macrocycles.
Figure 16: Macrocycles with diamide-diester groups (30).
Figure 17: C2-symmetric chiral aza-18-crown-6 ethers (31) with phenethylamine residues.
Figure 18: Chiral C-pivot p-methoxy-phenoxy-lariat ethers.
Figure 19: Chiral lariat crown ether 34.
Figure 20: Sucrose-based chiral crown ether receptors 36.
Figure 21: Permethylated fructooligosaccharide 37 showing induced-fit chiral recognition.
Figure 22: Biphenanthryl-18-crown-6 derivative 38.
Figure 23: Chiral lariat crown ethers derived from binol by Fuji et al.
Figure 24: Chiral phenolic crown ether 41 with “aryl chiral barriers” and guest amines.
Figure 25: Chiral bis-crown receptor 43 with a meso-ternaphthalene backbone.
Figure 26: Chromogenic pH-dependent bis-crown chemosensor 44 for diamines.
Figure 27: Triamine guests for binding to receptor 44.
Figure 28: Chiral bis-crown phenolphthalein chemosensors 46.
Figure 29: Crown ether amino acid 47.
Figure 30: Luminescent receptor 48 for bis-alkylammonium guests.
Figure 31: Luminescent CEAA (49a), a bis-CEAA receptor for amino acids (49b) and the structure of lysine bindi...
Figure 32: Luminescent CEAA tripeptide for binding small peptides.
Figure 33: Bis crown ether 51a self assembles co-operatively with C60-ammonium ion 51b.
Figure 34: Triptycene-based macrotricyclic dibenzo-[24]-crown-8 ether host 52 and guests.
Figure 35: Copper imido diacetic acid azacrown receptor 53a and the suggested His-Lys binding motif; a copper ...
Figure 36: Urea (54) and thiourea (55) benzo crown receptor for transport and extraction of amino acids.
Figure 37: Crown pyryliums ion receptors 56 for amino acids.
Figure 38: Ditopic sulfonamide bridged crown ether receptor 57.
Figure 39: Luminescent peptide receptor 58.
Figure 40: Luminescent receptor 59 for the detection of D-glucosamine hydrochloride in water/ethanol and lumin...
Figure 41: Guanidinium azacrown receptor 61 for simple amino acids and ditopic receptor 62 with crown ether an...
Figure 42: Chiral bicyclic guanidinium azacrown receptor 63 and similar receptor 64 for the enantioselective t...
Figure 43: Receptors for zwitterionic species based on luminescent CEAAs.
Figure 44: 1,10-Azacrown ethers with sugar podand arms and the anticancer agent busulfan.
Figure 45: Benzo-18-crown-6 modified β-cyclodextrin 69 and β-cyclodextrin functionalized with diaza-18-crown-6...
Figure 46: Receptors for colorimetric detection of primary and secondary ammonium ions.
Figure 47: Porphyrine-crown-receptors 72.
Figure 48: Porphyrin-crown ether conjugate 73 and fullerene-ammonium ion guest 74.
Figure 49: Calix[4]arene (75a), homooxocalix[4]arene (75b) and resorcin[4]arene (75c) compared (R = H, alkyl c...
Figure 50: Calix[4]arene and ammonium ion guest (R = H, alkyl, OAcyl etc.), possible binding sites; A: co-ordi...
Figure 51: Typical guests for studies with calixarenes and related molecules.
Figure 52: Lower rim modified p-tert-butylcalix[5]arenes 82.
Figure 53: The first example of a water soluble calixarene.
Figure 54: Sulfonated water soluble calix[n]arenes that bind ammonium ions.
Figure 55: Displacement assay for acetylcholine (3) with a sulfonato-calix[6]arene (84b).
Figure 56: Amino acid inclusion in p-sulfonatocalix[4]arene (84a).
Figure 57: Calixarene receptor family 86 with upper and lower rim functionalization.
Figure 58: Calix[6]arenes 87 with one carboxylic acid functionality.
Figure 59: Sulfonated calix[n]arenes with mono-substitution at the lower rim systematically studied on their r...
Figure 60: Cyclotetrachromotropylene host (91) and its binding to lysine (81c).
Figure 61: Calixarenes 92 and 93 with phosphonic acids groups.
Figure 62: Calix[4]arene tetraphosphonic acid (94a) and a double bridged analogue (94b).
Figure 63: Calix[4]arene tetraphosphonic acid ester (92c) for surface recognition experiments.
Figure 64: Calixarene receptors 95 with α-aminophosphonate groups.
Figure 65: A bridged homocalix[3]arene 95 and a distally bridged homocalix[4]crown 96.
Figure 66: Homocalix[3]arene ammonium ion receptor 97a and the Reichardt’s dye (97b) for colorimetric assays.
Figure 67: Chromogenic diazo-bridged calix[4]arene 98.
Figure 68: Calixarene receptor 99 by Huang et al.
Figure 69: Calixarenes 100 reported by Parisi et al.
Figure 70: Guest molecules for inclusion in calixarenes 100: DAP × 2 HCl (101a), APA (101b) and Lys-OMe × 2 HC...
Figure 71: Different N-linked peptido-calixarenes open and with glycol chain bridges.
Figure 72: (S)-1,1′-Bi-2-naphthol calixarene derivative 104 published by Kubo et al.
Figure 73: A chiral ammonium-ion receptor 105 based on the calix[4]arene skeleton.
Figure 74: R-/S-phenylalaninol functionalized calix[6]arenes 106a and 106b.
Figure 75: Capped homocalix[3]arene ammonium ion receptor 107.
Figure 76: Two C3 symmetric capped calix[6]arenes 108 and 109.
Figure 77: Phosphorous-containing rigidified calix[6]arene 110.
Figure 78: Calix[6]azacryptand 111.
Figure 79: Further substituted calix[6]azacryptands 112.
Figure 80: Resorcin[4]arene (75c) and the cavitands (113).
Figure 81: Tetrasulfonatomethylcalix[4]resorcinarene (114).
Figure 82: Resorcin[4]arenes (115a/b) and pyrogallo[4]arenes (115c, 116).
Figure 83: Displacement assay for acetylcholine (3) with tetracyanoresorcin[4]arene (117).
Figure 84: Tetramethoxy resorcinarene mono-crown-5 (118).
Figure 85: Components of a resorcinarene based displacement assay for ammonium ions.
Figure 86: Chiral basket resorcin[4]arenas 121.
Figure 87: Resorcinarenes with deeper cavitand structure (122).
Figure 88: Resorcinarene with partially open deeper cavitand structure (123).
Figure 89: Water-stabilized deep cavitands with partially structure (124, 125).
Figure 90: Charged cavitands 126 for tetralkylammonium ions.
Figure 91: Ditopic calix[4]arene receptor 127 capped with glycol chains.
Figure 92: A calix[5]arene dimer for diammonium salt recognition.
Figure 93: Calixarene parts 92c and 129 for the formation molecular capsules.
Figure 94: Encapsulation of a quaternary ammonium cation by two resorcin[4]arene molecules (NMe4+@[75c]2 × Cl−...
Figure 95: Encapsulation of a quaternary ammonium cation by six resorcin[4]arene molecules (NMe3D+@[130]6 × Cl−...
Figure 96: Structure and schematic of cucurbit[6]uril (CB[6], 131a).
Figure 97: Cyclohexanocucurbit[6]uril (CB′[6], 132) and the guest molecule spermine (133).
Figure 98: α,α,δ,δ-Tetramethylcucurbit[6]uril (134).
Figure 99: Structure of the cucurbituril-phthalhydrazide analogue 135.
Figure 100: Organic cavities for the displacement assay for amine differentiation.
Figure 101: Displacement assay methodology for diammonium- and related guests involving cucurbiturils and some ...
Figure 102: Nor-seco-Cucurbituril (±)-bis-ns-CB[6] (140) and guest molecules.
Figure 103: The cucurbit[6]uril based complexes 141 for chiral discrimination.
Figure 104: Cucurbit[7]uril (131c) and its ferrocene guests (142) opposed.
Figure 105: Cucurbit[7]uril (131c) guest inclusion and representative guests.
Figure 106: Cucurbit[7]uril (131c) binding to succinylcholine (145) and different bis-ammonium and bis-phosphon...
Figure 107: Paraquat-cucurbit[8]uril complex 149.
Figure 108: Gluconuril-based ammonium receptors 150.
Figure 109: Examples of clefts (151a), tweezers (151b, 151c, 151d) and clips (151e).
Figure 110: Kemp’s triacid (152a), on example of Rebek’s receptors (152b) and guests.
Figure 111: Amino acid receptor (154) by Rebek et al.
Figure 112: Hexagonal lattice designed hosts by Bell et al.
Figure 113: Bell’s amidinium receptor (156) and the amidinium ion (157).
Figure 114: Aromatic phosphonic acids.
Figure 115: Xylene phosphonates 159 and 160a/b for recognition of amines and amino alcohols.
Figure 116: Bisphosphonate recognition motif 161 for a colorimetric assay with alizarin complexone (163) for ca...
Figure 117: Bisphosphonate/phosphate clip 164 and bisphosphonate cleft 165.
Figure 118: N-Methylpyrazine 166a, N-methylnicotinamide iodide (166b) and NAD+ (166c).
Figure 119: Bisphosphate cavitands.
Figure 120: Bisphosphonate 167 of Schrader and Finocchiaro.
Figure 121: Tweezer 168 for noradrenaline (80b).
Figure 122: Different tripods and heparin (170).
Figure 123: Squaramide based receptors 172.
Figure 124: Cage like NH4+ receptor 173 of Kim et al.
Figure 125: Ammonium receptors 174 of Chin et al.
Figure 126: 2-Oxazolin-based ammonium receptors 175a–d and 176 by Ahn et al.
Figure 127: Racemic guest molecules 177.
Figure 128: Tripods based on a imidazole containing macrocycle (178) and the guest molecules employed in the st...
Figure 129: Ammonium ion receptor 180.
Figure 130: Tetraoxa[3.3.3.3]paracyclophanes 181 and a cyclophanic tetraester (182).
Figure 131: Peptidic bridged paraquat-cyclophane.
Figure 132: Shape-selective noradrenaline host.
Figure 133: Receptor 185 for binding of noradrenaline on surface layers from Schrader et al.
Figure 134: Tetraphosphonate receptor for binding of noradrenaline.
Figure 135: Tetraphosphonate 187 of Schrader and Finocchiaro.
Figure 136: Zinc-Porphyrin ammonium-ion receptors 188 and 189 of Mizutani et al.
Figure 137: Zinc porphyrin receptor 190.
Figure 138: Zinc porphyrin receptors 191 capable of amino acid binding.
Figure 139: Zinc-porphyrins with amino acid side chains for stereoinduction.
Figure 140: Bis-zinc-bis-porphyrin based on Tröger’s base 193.
Figure 141: BINAP-zinc-prophyrin derivative 194 and it’s guests.
Figure 142: Bisaryl-linked-zinc-porphyrin receptors.
Figure 143: Bis-zinc-porphyrin 199 for diamine recognition and guests.
Figure 144: Bis-zinc-porphyrin crown ether 201.
Figure 145: Bis-zinc-porphyrin 202 for stereodiscrimination (L = large substituent; S = small substituent).
Figure 146: Bis-zinc-porphyrin[3]rotaxane and its copper complex and guests.
Figure 147: Dien-bipyridyl ligand 206 for co-ordination of two metal atoms.
Figure 148: The ligand and corresponding tetradentate co-complex 207 serving as enantioselective receptor for a...
Figure 149: Bis(oxazoline)–copper(II) complex 208 for the recognition of amino acids in aqueous solution.
Figure 150: Zinc-salen-complexes 209 for the recognition tertiary amines.
Figure 151: Bis(oxazoline)–copper(II) 211 for the recognition of amino acids in aqueous solution.
Figure 152: Zn(II)-complex of a C2 terpyridine crown ether.
Figure 153: Displacement assay and receptor for aspartate over glutamate.
Figure 154: Chiral complex 214 for a colorimetric displacement assay for amino acids.
Figure 155: Metal complex receptor 215 with tripeptide side arms.
Figure 156: A sandwich complex 216 and its displaceable dye 217.
Figure 157: Lanthanide complexes 218–220 for amino acid recognition.
Figure 158: Nonactin (221), valinomycin (222) and vancomycin (223).
Figure 159: Monesin (224a) and a chiral analogue for enantiodiscrimination of ammonium guests (224b).
Figure 160: Chiral podands (226) compared to pentaglyme-dimethylether (225) and 18-crown-6 (4).
Figure 161: Lasalocid A (228).
Figure 162: Lasalocid derivatives (230) of Sessler et al.
Figure 163: The Coporphyrin I tetraanion (231).
Figure 164: Linear and cyclic peptides for ammonium ion recognition.
Figure 165: Cyclic and bicyclic depsipeptides for ammonium ion recognition.
Figure 166: α-Cyclodextrin (136a) and novocaine (236).
Figure 167: Helical diol receptor 237 by Reetz and Sostmann.
Figure 168: Ammonium binding spherand by Cram et al. (238a) and the cyclic[6]metaphenylacetylene 238b in compar...
Figure 169: Receptor for peptide backbone and ammonium binding (239).
Figure 170: Anion sensor principle with 3-hydroxy-2-naphthanilide of Jiang et al.
Figure 171: 7-bromo-3-hydroxy-N-(2-hydroxyphenyl)naphthalene 2-carboxamide (241) and its amine binding.
Figure 172: Naturally occurring catechins with affinity to quaternary ammonium ions.
Figure 173: Spiropyran (244) and merocyanine form (244a) of the amino acid receptors of Fuji et al.
Figure 174: Coumarin aldehyde (245) and its iminium species with amino acid bound (245a) by Glass et al.
Figure 175: Coumarin aldehyde appended with boronic acid.
Figure 176: Quinolone aldehyde dimers by Glass et al.
Figure 177: Chromogenic ammonium ion receptors with trifluoroacetophenone recognition motifs.
Figure 178: Chromogenic ammonium ion receptor with trifluoroacetophenone recognition motif bound on different m...
Concise methods for the synthesis of chiral polyoxazolines and their application in asymmetric hydrosilylation
- Wei Jie Li,
- Zun Le Xu and
- Sheng Xiang Qiu
Beilstein J. Org. Chem. 2010, 6, No. 29, doi:10.3762/bjoc.6.29
- concomitant removal of water or the alcohol produced in the reaction. The method is much simpler and more efficient in comparison to those methods reported in the literature. The compounds were used as chiral ligands in the rhodium-catalyzed asymmetric hydrosilylation of aromatic ketones, and the effects of
- the linkers and the substituents present on the oxazoline rings on the yield and enantioselectivity investigated. Compound 2 was identified as the best ligand of this family for the hydrosilylation of aromatic ketones. Keywords: aromatic ketone; hydrosilylation; polyoxazoline; rhodium; synthesis
- –7) are described, which are much simpler and more efficient in comparison to those reported in the literature. With these chiral ligands as templates, the rhodium-catalyzed asymmetric hydrosilylation of aromatic ketones was carried out. The effects of the linkers of oxazoline rings and the
Ring opening metathesis polymerization-derived block copolymers bearing chelating ligands: synthesis, metal immobilization and use in hydroformylation under micellar conditions
- Gajanan M. Pawar,
- Jochen Weckesser,
- Siegfried Blechert and
- Michael R. Buchmeiser
Beilstein J. Org. Chem. 2010, 6, No. 28, doi:10.3762/bjoc.6.28
- -yl (cyclooctadiene) rhodium chloride (C1) [9] were synthesized according to the literature. exo,exo-[2-(3-Ethoxycarbonyl-7-oxabicyclo[2.2.1]hept-5-en-2-carbonyloxy)ethyl]trimethylammonium iodide (M2) exo,exo-7-Oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid mono(2-dimethylaminoethyl) ester (1): exo
Graphical Abstract
Scheme 1: Synthesis of M2.
Scheme 2: Synthesis of poly(M1-b-M2) and of the micellar catalyst poly(M1-b-M2)-Rh.
Figure 1: Conversion (%) of 1-octene, product formation, product distribution, as well as time dependant n:iso...
Figure 2: Conversion of 1-octene, product formation and product distribution in the hydroformylation in water...
Iridium-catalyzed asymmetric ring-opening reactions of oxabicyclic alkenes with secondary amine nucleophiles
- Dingqiao Yang,
- Ping Hu,
- Yuhua Long,
- Yujuan Wu,
- Heping Zeng,
- Hui Wang and
- Xiongjun Zuo
Beilstein J. Org. Chem. 2009, 5, No. 53, doi:10.3762/bjoc.5.53
- alkenes is one of the most attractive because this reaction could potentially create two chiral centers in a single step. Pioneering work in this field was first described by Caple et al. [6] and the group of Lautens [7][8][9]. In the past decades, the group of Lautens and others reported rhodium
- -catalyzed asymmetric ring-opening of oxabenzonorbornadiene with a wide range of nucleophiles including thiols [10], phenols [11], organoboronic acids [12][13], dialkylzincs [14][15], carboxylates [16], sulfur nucleophiles [17], and various amines [18][19]. In addition to rhodium catalysts, other transition
- the desired products in moderate to good yields with good enantioselectivities. The iridium-catalyzed ARO reactions described in this article featured lower cost compared with rhodium-catalyzed ARO reactions, which provided potential applications in asymmetric synthesis of chiral building blocks. The
Graphical Abstract
Scheme 1: Identification of optimal chiral ligand for iridium-catalyzed asymmetric ring-opening of oxabenzono...
Figure 1: ORTEP plot for 3f.
Scheme 2: Proposed mechanism for the ARO of oxabenzonorbornadiene 1a with secondary amine nucleophiles.
Mitomycins syntheses: a recent update
- Jean-Christophe Andrez
Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33
- of the indoline intermediate to the indole. The regioselectivity is in accord with the results of Adams who showed that the C–H bond with the highest electron density was the most likely to migrate during rhodium(II) mediated C–H insertion [113]. A related study assessed the possibility of
Graphical Abstract
Scheme 1: Aziridine containing natural products.
Scheme 2: Mitomycin structures and nomenclature.
Scheme 3: Base catalysed epimerization of mitomycin B.
Scheme 4: Biosynthesis of mitomycin C (MMC) 7.
Scheme 5: Mode of action of mitomycin C.
Scheme 6: The N–C3–C9a disconnection.
Scheme 7: Danishefsky’s Retrosynthesis of mitomycin K.
Scheme 8: Hetero Diels–Alder reaction en route to mitomycins.
Scheme 9: Nitroso Diels–Alder cycloaddition.
Scheme 10: Frank azide cycloadddition.
Scheme 11: Final steps of mitomycin K synthesis. aPDC, DCM; bPhSCH2N3, PhH, 80 °C; cL-selectride, THF, −78 °C; ...
Scheme 12: Naruta–Maruyama retrosynthesis.
Scheme 13: Synthesis of a leucoaziridinomitosane by nitrene cycloaddition. aAlCl3-Et2O; bNaH, ClCH2OMe; cn-BuL...
Scheme 14: Thermal decomposition of azidoquinone 51.
Scheme 15: Diastereoselectivity during the cycloaddition.
Scheme 16: Oxidation with iodo-azide.
Scheme 17: Williams’ approach towards mitomycins.aDEIPSCl, Imidazole, DCM; bPd/C, HCO2NH4, MeOH; cAllocCl, NaH...
Scheme 18: Synthesis of pyrrolidones by homoconjugate addition.
Scheme 19: Homoconjugate addition on the fully functionalized substrate.
Scheme 20: Introduction of the olefin.
Scheme 21: Retrosynthesis of N–C9a, N–C3 bond formation.
Scheme 22: Synthesis of the pyrrolo[1,2]indole 82 using N-PSP activation.aAc2O, Py; bAc2O, Hg(OAc)2, AcOH, 90%...
Scheme 23: Synthesis of an aziridinomitosane. am-CPBA, DCM then iPr2NH, CCl4 reflux; bK2CO3, MeOH; cBnBr, KH; d...
Scheme 24: Oxidation products of a leucoaziridinomitosane obtained from a Polonovski oxidation.
Scheme 25: Polonovski oxidation of an aziridinomitosane. am-CPBA; bPd/C, H2; cDimethoxypropane, PPTS.
Scheme 26: The C1–C9a disconnection.
Scheme 27: Ziegler synthesis of desmethoxymitomycin A.aIm2C=O, THF; bNH3; cTMSOTf, 2,6-di-tert-butylpyridine, ...
Scheme 28: Transformation of sodium erythorbate.aTBDMSCl; bNaN3; cPPh3; d(Boc)2O, DMAP; eTBAF; fTf2O, Pyr.
Scheme 29: Formation of C9,C10-unsaturation in the mitomycins. am-CPBA, DCM; bO3, MeOH; cMe2S; dKHMDS, (EtO)3P...
Scheme 30: Fragmentation mechanism.
Scheme 31: Michael addition-cyclisation.
Scheme 32: SmI2 8-endo-dig cyclisation.
Scheme 33: Synthesis of pyrrolo[1,2-a]indole by 5-exo-dig radical cyclization.
Scheme 34: The C9–C9a disconnection.
Scheme 35: Intramolecular nitrile oxide cycloaddition.
Scheme 36: Regioselectivity of the INOC.
Scheme 37: Fukuyama’s INOC strategy.
Scheme 38: Synthesis of a mitosane core by rearrangement of a 1-(1-pyrrolidinyl)-1,3-butadiene.
Scheme 39: Sulikowski synthesis of an aziridinomitosene. aPd(Tol3P)2Cl2, Bu3SnF, 140; bH2, Pd/C; cTFAA, Et3N; d...
Scheme 40: Enantioselective carbene insertion.
Scheme 41: Parson’s radical cyclization.
Scheme 42: Cha’s mitomycin B core synthesis.
Scheme 43: The N-aromatic disconnection.
Scheme 44: Kishi retrosynthesis.
Scheme 45: Kishi synthesis of a starting material. aallyl bromide, K2CO3, acetone, reflux; bN,N-Dimethylanilin...
Scheme 46: Kishi synthesis of MMC 7. aLDA, THF, −78 °C then PhSeBr, THF, −78 °C; bH2O2, THF-EtOAc; cDIBAL, DCM...
Scheme 47: Acid catalyzed degradation of MMC 7.
Scheme 48: In vivo formation of apomitomycin B.
Scheme 49: Advanced intermediate for apomitomycin B synthesis.
Scheme 50: Remers synthesis of a functionalized mitosene. aTMSCl, Et3N, ZnCl2 then NBS; bAcOK; cNH2OH; dPd/C, H...
Scheme 51: Coleman synthesis of desmethoxymitomycin A. aSnCl2, PhSH, Et3N, CH3CN; bClCO2Bn, Et3N; cPPh3, DIAD,...
Scheme 52: Transition state and pyrrolidine synthesis.
Scheme 53: Air oxidation of mitosanes and aziridinomitosanes.
Scheme 54: The C9-aromatic disconnection.
Scheme 55: Synthesis of the aziridine precursor. aLHMDS, THF; bNaOH; c(s)-α-Me-BnNH2, DCC, HOBT; dDIBAL; eK2CO3...
Scheme 56: Synthesis of 206 via enamine conjugate addition.
Scheme 57: Rapoport synthesis of an aziridinomitosene.
Scheme 58: One pot synthesis of a mitomycin analog.
Scheme 59: Synthesis of compound 218 via intramolecular Heck coupling. aEtMgCl, THF, then 220; bMsCl, Et3N; cN...
Scheme 60: Elaboration of indole 223. aEt3N, Ac2O; bAcOH; cSOCl2, Et3N; dNaN3, DMF; eH2SO4, THF; fK2CO3, MeOH; ...
Scheme 61: C9-C9a functionalization from indole.
Scheme 62: Synthesis of mitomycin K. a2 equiv. MoO5.HMPA, MeOH; bPPh3, Et3N, THF-H2O; cMeOTf, Py, DCM; dMe3SiCH...
Scheme 63: Configurational stability of mitomycin K derivatives.
Scheme 64: Epimerization of carbon C9a in compound 227b.
Scheme 65: Corey–Chaykovsky synthesis of indol 235.
Scheme 66: Cory intramolecular aza-Darzens reaction for the formation of aziridinomitosene 239.
Scheme 67: Jimenez synthesis of aziridinomitosene 242.
Scheme 68: Von Braun opening of indoline 244.
Scheme 69: C9a oxidation of an aziridinomitosane with DDQ/OsO4.
Scheme 70: Synthesis of epi-mitomycin K. aNaH, Me2SO4; bH2, Pd/C; cMitscher reagent [165]; d[(trimethylsilyl)methyl...
Scheme 71: Mitomycins rearrangement.
Scheme 72: Fukuyama’s retrosynthesis.
Scheme 73: [2+3] Cycloaddition en route to isomitomycin A. aToluene, 110 °C; bDIBAL, THF, −78 °C; cAc2O, Py.; d...
Scheme 74: Final steps of Fukuyama’s synthesis.
Scheme 75: “Crisscross annulation”.
Scheme 76: Synthesis of 274; the 8-membered ring 274 was made using a crisscross annulation. a20% Pd(OH)2/C, H2...
Scheme 77: Conformational analysis of compound 273 and 275.
Scheme 78: Synthesis of a mitomycin analog. aNa2S2O4, H2O, DCM; bBnBr (10 equiv), K2CO3, 18-crown-6 (cat.), TH...
Scheme 79: Vedejs retrosynthesis.
Scheme 80: Formation of the azomethine ylide.
Scheme 81: Vedejs second synthesis of an aziridinomitosene. aDIBAL; bTPAP, NMO; c287; dTBSCl, imidazole.
Scheme 82: Trityl deprotection and new aziridine protecting group 300.
Scheme 83: Ene reaction towards benzazocinones.
Scheme 84: Benzazocenols via homo-Brook rearrangement.
Scheme 85: Pt-catalyzed [3+2] cycloaddition.
Scheme 86: Carbonylative lactamization entry to benzazocenols. aZn(OTf)2, (+)-N-methylephedrine, Et3N, TMS-ace...
Scheme 87: 8 membered ring formation by RCM. aBOC2O, NaHCO3; bTBSCl, Imidazole, DMF; callyl bromide, NaH, DMF; ...
Scheme 88: Aziridinomitosene synthesis. aTMSN3; bTFA; cPOCl3, DMF; dNaClO2, NaH2PO4, 2-methyl-2-butene; eMeI, ...
Scheme 89: Metathesis from an indole.
Scheme 90: Synthesis of early biosynthetic intermediates of mitomycins.
Asymmetric reactions in continuous flow
- Xiao Yin Mak,
- Paola Laurino and
- Peter H. Seeberger
Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19
- screened for reactivity and enantioselectivity with the rhodium catalyst [Rh(COD)2]BF4 within a 3 min residence time. With this device, very low catalyst/ligand loadings were used per run (ca. 0.1 μg of Rh catalyst), providing reliably reproducible results. Reactivity in the microreactor was found to be
Graphical Abstract
Scheme 1: Enantioselective addition of trimethylsilyl cyanide to benzaldehyde.
Scheme 2: Asymmetric catalytic hydrogenation in a falling-film microreactor.
Scheme 3: Aldol reaction catalyzed by 5-(pyrrolidine-2-yl)tetrazole.
Scheme 4: Enantioselective addition of diethylzinc to aryl aldehydes.
Scheme 5: Glyoxylate-ene reaction in flow.
Scheme 6: Asymmetric synthesis of ß-lactams.
Scheme 7: α-Chlorination of acid chlorides in flow.
Scheme 8: Asymmetric Michael reaction in continuous flow.
Scheme 9: Enantioselective addition of Et2Zn to benzaldehyde using monolithic chiral amino alcohol.
Scheme 10: Continuous-flow hydrolytic dynamic kinetic resolution of epibromohydrin (32).
Scheme 11: Continuous-flow asymmetric cyclopropanation.
Scheme 12: Continuous asymmetric hydrogenation of dimethyl itaconate in scCO2.
Scheme 13: Continuous asymmetric transfer hydrogenation of acetophenone.
Scheme 14: Asymmetric epoxidation using a continuous flow membrane reactor.
Scheme 15: Enzymatic cyanohydrin formation in a microreactor.
Scheme 16: Resolution of (R/S)- 54 with immobilized lipase in a continuous scCO2- flow reactor.
Scheme 17: Enantioselective separation of Acetyl-D-Phe in a continuous flow reactor.
One-pot preparation of substituted pyrroles from α-diazocarbonyl compounds
- Fernando de C. da Silva,
- Mauricio G. Fonseca,
- Renata de S. Rianelli,
- Anna C. Cunha,
- Maria C. B. V. de Souza and
- Vitor F. Ferreira
Beilstein J. Org. Chem. 2008, 4, No. 45, doi:10.3762/bjoc.4.45
- quantity of rhodium(II) acetate in the presence of butyl vinyl ether to produce the corresponding 3-carbonyl-dihydrofurans 4–6. The rhodium catalyzed reaction of the α-diazocarbonyl compounds 1–3 was monitored by TLC chromatography. Evaporation of the solvents at the end of these reactions followed by
Synthesis of (–)-Indolizidine 167B based on domino hydroformylation/cyclization reactions
- Giuditta Guazzelli,
- Raffaello Lazzaroni and
- Roberta Settambolo
Beilstein J. Org. Chem. 2008, 4, No. 2, doi:10.1186/1860-5397-4-2
- Indolizidine 167B depicted here the construction of the bicyclic core still occurs via a pyrrolylbutanal; unlike the previous case, the aldehyde comes from rhodium-catalyzed hydroformylation of optically active (R)-3-(pyrrol-1-yl)hex-1-ene (1) (Scheme 1). The formed linear aldehyde 2a (Scheme 2), bearing an n
- reduction gives the target compound (ee 92%) (Scheme 1). The rhodium-catalyzed hydroformylation of olefins is an important industrial tool for the production of aldehydes [10][11]. During the last few years, the oxo process has been employed also in the synthesis of fine chemicals especially integrated in
- heteroaromatic olefins has a topic of our research for many years [15][16][17][18][19]; now it is the first time that the rhodium catalyzed hydroformylation is employed by us in the total synthesis of a target compound and as a key reaction in a domino process with a high number of steps. Results and Discussion
Graphical Abstract
Figure 1: (–)-Indolizidine 167B.
Scheme 1: Reagents: i Rh4(CO)12, 30 atm CO:H2 = 1:1, 125 °C, toluene, 24 min, 76% yield; ii the same conditio...
Scheme 2: Stereospecific interconversion of the rhodium-alkyl intermediates as the key for regioselective for...
The use of silicon- based tethers for the Pauson- Khand reaction
- Adrian P. Dobbs,
- Ian J. Miller and
- Saša Martinović
Beilstein J. Org. Chem. 2007, 3, No. 21, doi:10.1186/1860-5397-3-21
- being reacted with each of molybdenum hexacarbonyl/DMSO[21]; tungsten pentacarbonyl/THF[22]; chromium hexacarbonyl and rhodium cycloooctadiene chloride dimer/pentafluorobenzaldehyde[23][24]. None of the promoters gave any Pauson-Khand adducts, although an interesting THF-insertion adduct was obtained
Graphical Abstract
Scheme 1: Saigo's cycloisomerisation reaction under Pauson-Khand conditions.
Scheme 2: Pauson-Khand reaction and tether-cleavage in wet acetonitrile.
Scheme 3: Silyl-tethered allenic Pauson-Khand reaction reported by Brummond.
Scheme 4: Intramolecular Pauson-Khand reaction of allyldimethyl- and allyldiphenylsilyl propargyl ethers repo...
Scheme 5: Synthesis and attempted Pauson-Khand reactions of vinyldimethylsilyl- and vinyldiphenylsilyl ethers....
Figure 1: Functionalised acetylenes prepared and used in silyl ether-tethered Pauson-Khand reactions. Yields ...
Figure 2: Chain-functionalised acetylenes prepared and used in silyl ether-tethered Pauson-Khand reactions. Y...
Figure 3: Possible structure of THF-oxidation/insertion product.
Scheme 6: Model Pauson-Khand reaction of allyltrimethylsilane.
Scheme 7: Preparation of allyldiisopropylsilyl ethers.
Scheme 8: Pauson-Khand reaction of allyldiisopropylsilyl ethers.
Scheme 9: Preparation of allyldiisopropylsilanes.
Scheme 10: Attempted Mitsunobu reactions of diisopropylsilanols.
Scheme 11: Preparation of alkynic diisopropylsilanes.
Scheme 12: Preparation of allyldiisopropylsilyl ethers.
Scheme 13: Preparation of acetals from dichlorodiphenylsilane.
Scheme 14: Attempted Pauson-Khand reaction of allylpropargyldiphenylsilyl acetal.
Scheme 15: Proposed diisopropylsilyl acetal formation.
Scheme 16: Attempted allylpropargyldiisopropylsilyl acetal formation.
Scheme 17: Attempted allylpropargyldiisopropylsilyl acetal formation.
Scheme 18: Preparation of silicon-tethered Pauson-Khand precursors.
Scheme 19: Failed Pauson-Khand reaction of a silicon-tethered substrate.
Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes
- Stephen P. Marsden and
- Pascal C. Ducept
Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5
- prepared through rhodium(II)-mediated rearrangement of silylated diazoketones. Results A range of novel 1,3-disubstituted and 1,3,3-trisubstituted allenylsilanes were prepared using stabilised and semi-stabilised ylides. Alkylidenation with non-stabilised phosphorus ylides was not viable, but the use of
- functional group tolerant approach to substituted silylketenes based upon a rhodium-mediated formal Wolff rearrangement of silylated diazoketones.[23] Related photolytic approaches also hold some promise.[24][25][26][27] These methods allow access for the first time to a wide range of substituted
- our previously reported conditions for rhodium(II) octanoate-mediated rearrangement of silyl diazoketones 2,[23] which in turn were prepared by C-silylation of the parent diazoketones 3 with triethylsilyl triflate,[28] Scheme 1, Table 1. It should be noted that while the alkyl-substituted silylketenes
Graphical Abstract
Figure 1: Alkylidenation approach to the synthesis of allenylsilanes.
Scheme 1: Synthesis of substituted silylketenes 1
Scheme 2: Reaction of substituted silylketenes with ester-stabilised phosphoranes
Scheme 3: Reaction of silylketenes with various ylides
Scheme 4: Methylenation of silylketene 1b with the Lombardo reagent
Scheme 5: Methylenation of silylketenes with the Petasis reagent
