Magnesium bis(monoperoxyphthalate) hexahydrate as mild and efficient oxidant for the synthesis of selenones

• Andrea Temperini,
• Massimo Curini,
• Ornelio Rosati and
• Lucio Minuti

Beilstein J. Org. Chem. 2014, 10, 1267–1271, doi:10.3762/bjoc.10.127

• Abstract A new, efficient and mild method for the direct oxidation of selenides to selenones using magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) has been developed. Noteworthy this transformation proceeds at room temperature, employs a cheap and safety oxidant and has a broad functional group

• investigated the use of magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) as a new oxidant for the straightforward conversion of selenides 1 to selenones 2 under mild experimental conditions. Magnesium bis(monoperoxyphthalate) hexahydrate is a cheap commercially available, relatively stable and easy to use

• corresponding selenone in 68% yield. It is noteworthy that the reaction byproduct magnesium phthalate is water soluble and easy to separate during work-up; acidification of the water phase and extraction with dichloromethane allows to recover the pure phthalic acid in excellent yield. This protocol was then

Amino acid motifs in natural products: synthesis of O-acylated derivatives of (2S,3S)-3-hydroxyleucine

• Oliver Ries,
• Martin Büschleb,
• Markus Granitzka,
• Dietmar Stalke and
• Christian Ducho

Beilstein J. Org. Chem. 2014, 10, 1135–1142, doi:10.3762/bjoc.10.113

• derivative with limited stability, which was immediately converted into alcohol 4 by diastereoselective Felkin–Anh type Grignard addition with isopropyl magnesium chloride (50% yield over 2 steps from 3, dr > 95:5). However, we could not confirm that the use of diethyl ether as co-solvent in the Grignard

• acyclic D-serinal derivatives for the addition of nucleophiles to amino acid-derived aldehydes [33][34]. However, Zhu and co-workers have pointed out that Garner’s aldehyde surprisingly furnishes the syn diastereomer as the major product from its reaction with isopropyl magnesium chloride [32], thus

• formation of 8 in moderate to good yields (Table 1, entries 4–6). Finally, when 2,2-DiMP was used as solvent with catalytic amounts of CSA in the presence of magnesium sulfate, 8 could be isolated in a very good yield of 93% (Table 1, entry 7). After TBAF-mediated cleavage of the silyl ether, the resultant

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

A new building block for DNA network formation by self-assembly and polymerase chain reaction

• Holger Bußkamp,
• Sascha Keller,
• Marta Robotta,
• Malte Drescher and
• Andreas Marx

Beilstein J. Org. Chem. 2014, 10, 1037–1046, doi:10.3762/bjoc.10.104

• denaturation studies (cf. Figure 2). The self-complementary oligonucleotides (5 μM) were annealed in 10 mM triethylammonium acetate buffer at pH 7 in the presence of sodium chloride (150 mM), sodium chloride and magnesium chloride (150 mM and 100 mM, respectively) or in the absence of salts. The solutions were

• melting in all buffers tested (data not shown). In magnesium ion-containing buffer the CG 2-mer (ODN-sc-I) shows a higher melting temperature (37.6 °C) as the ODN-sc-II 4-mer (24.3 °C). The GC-rich 4-mer ODN-sc-III shows high melting temperatures even in the presence of only sodium chloride (58.0 °C) and

• an even higher melting temperature in the presence of additional magnesium (73.0 °C). The melting temperature in presence of sodium chloride and magnesium is even higher than the respective melting temperature of the 6-mer ODN-sc-IV (50.7 °C). All in all, one can conclude that the self-assembly of GC

N-Alkylated dinitrones from isosorbide as cross-linkers for unsaturated bio-based polyesters

• Oliver Goerz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 902–909, doi:10.3762/bjoc.10.88

• product was received after drying of the organic layer over magnesium sulfate and subsequent removal of the solvent under reduced pressure. Yield: 94%. 1H NMR (300 MHz, CDCl3) δ (ppm) 6.58–6.33 (m, 2H, H2C=CH-), 6.22–6.01 (m, 2H, H2C=CH-), 5.89–5.80 (m, 2H, H2C=CH-), 5.29–5.16 (m, 2H, -CH-O-CO-), 4.87 (t

• solution and the organic layer was dried over magnesium sulfate. The pure product was obtained by evaporation of the solvent. Yield: 92%. 1H NMR (300 MHz, CDCl3) δ (ppm) 7.11–6.94 (m, H3C-HC=CH-), 5.96–5.79 (m, 1H, H3C-HC=CH-), 5.33–5.08 (m, 2H, -CH-O-CO-), 4.86 (t, 3J = 5 Hz, 1H, -CH-CH-), 4.53 (d, 3J

Structure elucidation of female-specific volatiles released by the parasitoid wasp Trichogramma turkestanica (Hymenoptera: Trichogrammatidae)

• Armin Tröger,
• Teris A. van Beek,
• Martinus E. Huigens,
• Isabel M. M. S. Silva,
• Maarten A. Posthumus and
• Wittko Francke

Beilstein J. Org. Chem. 2014, 10, 767–773, doi:10.3762/bjoc.10.72

• , 10 h; c: p-TsCl, DMAP, TEA, DCM, −20 °C to rt, 12 h; d: (3-methylbutyl)magnesium bromide, CuI, THF, −90 °C to rt, 16 h; e: TBAF, THF, rt, 14 h; f: PDC, MS 4 Å, DCM, −20 °C, 90 min; g: (3-methylbut-2-en-1-yl)triphenylphosphonium bromide, n-BuLi, THF, −40 °C to rt 16 h; h: 1) NaH, THF, −20 °C to rt, 1

Synthesis of chiral N-phosphinyl α-imino esters and their application in asymmetric synthesis of α-amino esters by reduction

• Yiwen Xiong,
• Haibo Mei,
• Lingmin Wu,
• Jianlin Han,
• Yi Pan and
• Guigen Li

Beilstein J. Org. Chem. 2014, 10, 653–659, doi:10.3762/bjoc.10.57

• phosphinyl amide 1 (Table 1). Common dehydrating reagents, like 4 Å molecular sieves and magnesium sulfate, resulted in no desired product neither at room temperature nor under reflux (Table 1, entries 1–4). Very poor chemical yields of α-imino ester 3a were detected when tetraethoxytitanium or

Synthesis of complex intermediates for the study of a dehydratase from borrelidin biosynthesis

• Frank Hahn,
• Nadine Kandziora,
• Steffen Friedrich and
• Peter F. Leadlay

Beilstein J. Org. Chem. 2014, 10, 634–640, doi:10.3762/bjoc.10.55

• presence of a methyl ester function. Amongst others, we tested Paterson’s lactate-derived benzoyl auxiliary, Evans’ magnesium-catalyzed direct aldol reaction, and an Abiko–Masamune-like aldol reaction by using a thiodesoxy variant of the norephedrine-derived auxiliary on simplified model aldehydes as well

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• catalysts for coupling arylaldehydes, piperidine and phenylacetylene in toluene at 100 °C. One year later, the same research group obtained comparable results under identical reaction conditions by using gold(0) nanoparticles stabilized by nanocristalline magnesium oxide [28]. In this work, the scope was

• G–NH2 groups under palladium/copper [61][62], copper [63][64], copper/magnesium [65], or base [66] catalysis have been reported. When tosylhydrazide (41) is used as G–NH2 component, the silver promoted MCR can afford 2-amino-1,3-disubstituted-1,2-dihydroquinolines and, when the third component (Nu

Synthesis of the B-seco limonoid core scaffold

• Hanna Bruss,
• Hannah Schuster,
• Rémi Martinez,
• Markus Kaiser,
• Andrey P. Antonchick and
• Herbert Waldmann

Beilstein J. Org. Chem. 2014, 10, 194–208, doi:10.3762/bjoc.10.15

• envisaged to be constructed by 1,2-addition, using the free β-hydroxy functionality in 63 as directing group. Several conditions with allyl boronates, stannanes, silanes, indium, magnesium bromide, cerium, zinc bromide and other reagents have been screened. Finally, the best result was achieved with

Continuous-flow Heck synthesis of 4-methoxybiphenyl and methyl 4-methoxycinnamate in supercritical carbon dioxide expanded solvent solutions

• Phei Li Lau,
• Ray W. K. Allen and
• Peter Styring

Beilstein J. Org. Chem. 2013, 9, 2886–2897, doi:10.3762/bjoc.9.325

• susceptible to decomposition. Unfortunately, an excess of phosphine reduces the reaction rate, while higher quantities of palladium result in potentially significant increased production costs [33]. Palladium on a magnesium–lanthanum mixed oxide support (Pd/MgLaO) was reported to be an efficient, thermally

• . The resulting organic mixture (top layer) was then withdrawn and dried over magnesium sulfate then analysed by gas chromatography using a Varian 3900 GC with reference to standard solutions of trans-4-methoxystilbene. Continuous flow reactions Particles of the catalyst, 2% Pd on silica, (250 mg

N,N'-(Hexane-1,6-diyl)bis(4-methyl-N-(oxiran-2-ylmethyl)benzenesulfonamide): Synthesis via cyclodextrin mediated N-alkylation in aqueous solution and further Prilezhaev epoxidation

• Julian Fischer,
• Simon Millan and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2834–2840, doi:10.3762/bjoc.9.318

• % sodium bisulfite. Then, the organic phase was treated twice with 50 mL each of sodium hydrogen carbonate solution and stirred for 1.5 h. Subsequently, the organic phase was dried over magnesium sulfate and the solvent removed under reduced pressure to obtain 1.7 mmol (57% yield, not optimized) of 6. 1H

Oligomeric epoxide–amine adducts based on 2-amino-N-isopropylacetamide and α-amino-ε-caprolactam: Solubility in presence of cyclodextrin and curing properties

• Julian Fischer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 2803–2811, doi:10.3762/bjoc.9.315

• refluxed for 3 h and stirred at room temperature overnight. The phases were separated, the aqueous phase was washed twice with 30 mL of methylene chloride and the organic phases were combined. After drying over magnesium sulfate and filtration thereof methylene chloride was distilled off under reduced

Diastereoselectivity in the Staudinger reaction of pentafluorosulfanylaldimines and ketimines

• Alexander Penger,
• Cortney N. von Hahmann,
• Alexander S. Filatov and
• John T. Welch

Beilstein J. Org. Chem. 2013, 9, 2675–2680, doi:10.3762/bjoc.9.303

• converted to the corresponding imine 5 in dichloromethane using anhydrous magnesium sulfate as a dehydrating agent (Scheme 2). Other desiccants, especially inherently basic materials, such as potassium carbonate lead to little imine formation. While the crude imine solution likely contained unreacted amine

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• a moderate 5:1 anti/syn-selectivity. By changing the metal to magnesium (vinylMgBr) the selectivity slightly dropped to 3:1 (anti/syn) still favouring adduct 20. Addition of a Lewis acid (TiCl4) did not affect the diastereoselectivity with vinyllithium species. The addition of vinyllithium to (S)-1

Cu-catalyzed trifluoromethylation of aryl iodides with trifluoromethylzinc reagent prepared in situ from trifluoromethyl iodide

• Yuzo Nakamura,
• Motohiro Fujiu,
• Tatsuya Murase,
• Yoshimitsu Itoh,
• Hiroki Serizawa,
• Kohsuke Aikawa and
• Koichi Mikami

Beilstein J. Org. Chem. 2013, 9, 2404–2409, doi:10.3762/bjoc.9.277

• organometallic reagents such as lithium and magnesium, which are widely utilized in non-fluorine organic synthesis, cannot be used. These trifluoromethyl metal reagents are generally too unstable to prepare even at low temperature because of facile α-fluoro elimination generating the singlet difluoromethylene

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• thiazolidinedione 1.48 in the presence of a catalytic amount of piperidinium acetate reportedly leads to the exclusive formation of the desired Z-isomer product. Interestingly, the newly installed double bond was efficiently reduced using magnesium in methanol thus circumventing catalyst poisoning issues pertaining

• circumventing the problem describes the use of bench stable magnesium nitride, a solid material which upon hydrolysis liberates the required ammonia in situ (Scheme 23) [64]. However, there have been several reports on explosions caused by runaway reactions so extreme care must be administrated when using this

Post-Ugi gold-catalyzed diastereoselective domino cyclization for the synthesis of diversely substituted spiroindolines

• Amit Kumar,
• Dipak D. Vachhani,
• Sachin G. Modha,
• Sunil K. Sharma,
• Virinder S. Parmar and
• Erik V. Van der Eycken

Beilstein J. Org. Chem. 2013, 9, 2097–2102, doi:10.3762/bjoc.9.246

• mL). The organic layer was washed with brine (50 mL), dried over magnesium sulfate, and evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography (10% diethyl ether in dichloromethane) to afford compound 6a–q. Gold-catalyzed approaches towards

The chemistry of isoindole natural products

• Klaus Speck and
• Thomas Magauer

Beilstein J. Org. Chem. 2013, 9, 2048–2078, doi:10.3762/bjoc.9.243

• reduction, acetylation and a magnesium sulfate induced rearrangement of the epoxide to the allylic alcohol. The synthesis of cytochalasin B 52 (15 steps from 73) proceeded in a similar fashion and was highlighted in detail by Hertweck [44]. The authors state that this approach is highly diversifiable and

Organocatalyzed enantioselective desymmetrization of aziridines and epoxides

• Ping-An Wang

Beilstein J. Org. Chem. 2013, 9, 1677–1695, doi:10.3762/bjoc.9.192

• with aq HCl to generate metal-free chiral phosphoric acid OC-21, which was reused as the catalyst, and the corresponding ring-opening products were obtained in moderate yields as racemates. By using a 1:1 mixture of calcium and magnesium phosphate salts of OC-21 as the catalyst, the corresponding ring

• -opening product 28 was produced in 94% yield and 91% ee. Therefore, calcium and magnesium phosphate salts of OC-21 proved to be the true catalysts in these processes. The author suggested that these metal phosphates may be generated through the purification of OC-21 on silica gel column. A dual Lewis-base

Controlled synthesis of poly(3-hexylthiophene) in continuous flow

• Helga Seyler,
• Jegadesan Subbiah,
• David J. Jones,
• Andrew B. Holmes and
• Wallace W. H. Wong

Beilstein J. Org. Chem. 2013, 9, 1492–1500, doi:10.3762/bjoc.9.170

• thiophene Grignard monomer 2 is prepared from the magnesium exchange reaction of an alkyl Grignard reagent and 2,5-dibromo-3-hexylthiophene (1, Scheme 1a). It should be noted here that a mixture of Grignard monomers 2a and 2b is produced in this step, typically in a ratio of 75:25. Only 2a participates in

Hypervalent iodine/TEMPO-mediated oxidation in flow systems: a fast and efficient protocol for alcohol oxidation

• Nida Ambreen,
• Ravi Kumar and
• Thomas Wirth

Beilstein J. Org. Chem. 2013, 9, 1437–1442, doi:10.3762/bjoc.9.162

• time of 4.5 min. The reaction mixture exiting the flow reactor was quenched with water and, after completion of the reaction, extracted with CH2Cl2. The combined organic layers were dried over magnesium sulfate and the solvents were removed in vacuo. Direct analysis with GC allowed the determination of

• had been achieved, 200 mL of the reaction solution was collected in a flask containing water (20 mL) as a quenching agent. After completion of the reaction, the organic phase was removed and the aqueous phase was extracted with CH2Cl2 (3 × 20 mL). The combined organic layers were dried over magnesium

• . After the completion of the reaction the solvent was evaporated, and the reaction mixture was extracted with CH2Cl2 and water. The organic layers were dried over magnesium sulfate and the solvents were removed in vacuo. The 1H NMR analysis showed a clean spectrum of the condensation product. Flow setup

Total synthesis of ochnaflavone

• Monica M. Ndoile and
• Fanie R. van Heerden

Beilstein J. Org. Chem. 2013, 9, 1346–1351, doi:10.3762/bjoc.9.152

• was added, and the mixture was extracted with 3 × 20 mL CHCl3. The organic layer was dried over anhydrous magnesium sulfate, and the solvent was removed in vacuo. The residue obtained was purified by silica-gel column chromatography (EtOAc/hexanes, 3:7) as eluent to yield 748 mg (89%) of 4 as a light

• added, followed by extraction with 3 × 20 mL CHCl3. The obtained organic layer was dried over anhydrous magnesium sulfate, and the solvent was removed in vacuo. The residue was purified by silica gel column chromatography (EtOAc/hexanes, 1:9) to afford 5 (291 mg, 50%) as a white solid. 1H NMR (400 MHz

• anhydrous magnesium sulfate. CH2Cl2 was removed in vacuo and the resulting residue was purified by silica-gel column chromatography with EtOAc/hexanes (1:1) to afford 100 mg (25%) of the ether-linked biflavanone 8 as a light-yellow solid. 1H NMR (400 MHz, CDCl3) δH 7.40 (d, J = 8.5 Hz, 2H), 7.26 (dd, J

Exploration of an epoxidation–ring-opening strategy for the synthesis of lyconadin A and discovery of an unexpected Payne rearrangement

• Brad M. Loertscher,
• Yu Zhang and
• Steven L. Castle

Beilstein J. Org. Chem. 2013, 9, 1179–1184, doi:10.3762/bjoc.9.132

• in Scheme 6. Coordination of a Lewis acid (likely a copper or magnesium species) to the trityl ether moiety of 25 could promote migration of the trityl group [31][32] to the epoxide, generating intermediate A. Payne rearrangement of A would then furnish epoxide B. Finally, attack of the vinylcopper

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• enone 10 (>10 grams) for further functionalization. Conversion of 10 to 9 was accomplished based on our previously reported strategy (Scheme 3) [25]. Treatment of 10 with magnesium methyl carbonate (MMC) [79][80][81] yielded the C-5 carboxylic acid that, without further purification, was esterified