Synthesis of esters ofpara-hydroxy substituted α-trifluoromethylmandelic acids

Methyl trifluoropiruvate in trifluoroacetic acid at 20 °C rapidly C-hydroxyalkylates various phenols at thepara-positions to afford the corresponding esters ofpara-hydroxy substituted -trifluoromethylmandelic acids.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 528–530, March, 1995.The present study was carried out with the financial support of the Russian Foundation for Basic Research (Project code 93-03-22696).     

Oxidation of bicyclic monoterpene ketones with Caro’s acid

Previously unknown seven-membered lactones, (1R,1??R,5S,5??S)-5,5??-oxybis(1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one), 2,2-dimethyl-1,6-dioxaspiro[2.6]nonan-7-one, 4-(1-hydroxy-1-methylethyl)-7-methyloxepan-2-one, and (4R,4??R,7S,7??S)-4,4??-[oxybis(propane-2,2-diyl)]bis(7-methyloxepan-2-one), were synthesized by the Baeyer-Villiger reaction using Caro??s acid as a result of oxidative and skeletal transformations of bicyclic monoterpene ketones, (+)-camphor, (+)-nopinone, and (?)-isocaranone.     

Ru-catalyzed asymmetric hydrogenation of γ-heteroatom substituted β-keto esters

A series of enantiomerically pure γ-heteroatom substituted β-hydroxy esters were synthesized with high enantioselectivities (up to 99.1% ee) by hydrogenation of γ-heteroatom substituted β-keto esters in the presence of Ru-(S)-SunPhos catalyst. These asymmetric hydrogenations provide key building blocks for a variety of naturally occurring and biologically active compounds.     

A Mild and Efficient Oxidation of Alcohols in Water

A mild and efficient oxidation of alcohols to the corresponding carbonyl compounds using the PhI(OAc)2 (1.1 eq.) with n-Bu4NBr (8 mol %) in water at room temperature is described.This new procedure is very simple and affords the desired carbonyl compounds in high yields.     

A convenient procedure for the preparation of Garner’s aldehyde

The palladium/silane reduction of a serine thioester derivative allows for the preparation of enantiomerically pure Garner’s aldehyde from serine, in gram quantities within 24 h.     

Preparative synthesis of functionally substituted esters of dehydroabietic and 4,4′-biphenyldicarboxylic acids

A preparative synthesis of functionally substituted esters of dehydroabietic and 4,4-biphenylcarboxylic acids by the reaction of chlorides of these acids with alcohols in the presence of pyridine is developed. 4,4-Biphenyldicarbonyl dichloride reacts with hydroperoxides to form peroxy esters and with lithium alcoholates, which allows preparation of the corresponding ethers derived from secondary and tertiary alcohols.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1360–1364.Original Russian Text Copyright © 2004 by Dikusar, Yuvchenko, Kozlov, Olkhovik, Potkin.This revised version was published online in April 2005 with a corrected cover date.     

The setereoselective preparation of β-keto esters using baker＇s yeast in the presence of rice wine koji

By the addition of rice wine koji, enhancement of the reactivity was observed for the baker＇s yeast reduction of β-keto esters into （S）-β-hydroxy esters with high enantiomeric purity （73-98%）.     

Efficient synthetic method for the preparation of allyl- and propargyl-epoxides by allylation and propargylation of α-haloketones with organozinc reagents

A simple, efficient, and non-metal catalyzed synthetic method for the preparation of substituted allyl- and propargyl-epoxides by allylation and propargylation of α-halo ketones with organozinc reagents in mild conditions is reported in this paper. The present method complements the existing synthetic methods due to some advantageous properties of the organozinc reagents such as availability, selectivity, operational simplicity and low toxicity.     

Efficient preparation of β-hydroxy aspartic acid and its derivatives

We reported an efficient and practical synthetic route to various properly-protected erythreo-β-OH-Asp compounds, which are key β-branched a-amino acid units in coralmycin A and other peptide natural products.     

Synthesis of β-keto esters in-flow and rapid access to substituted pyrimidines

We have developed an in-flow process for the synthesis of β-keto esters via the BF(3)·OEt(2)-catalyzed formal C-H insertion of ethyl diazoacetate into aldehydes. The β-keto esters were then condensed with a range of amidines to give a variety of 2,6-substituted pyrimidin-4-ols.     

Baker''''s yeast mediated reduction of substituted acenaphthenequinones: Regio-and enantioselective preparation of mono-hydroxyacenaphthenones

Baker's yeast mediated reduction of acenaphthenequinone within 4-10 h afforded mono-hydroxyacenaphthenone mainly with low enantioselectivity, the substrate and mono-hydroxyacenaphthenone product almost converted to dihydroxyacenaphthene after 48 h. By control of the reaction time and in the presence of DMF as co-solvent, the reduction of 6-substituted acenaphthenequinones under vigorous agitation afforded the corresponding 2-hydroxyacenaphthenones in 24-84% yields with 10-93% ee.     

Efficient magnetic CoFe2O4 nanocrystal catalyst for aerobic oxidation of cyclohexane prepared by sol–gel auto-combustion method: effects of catalyst preparation parameters

Six magnetic spinel-type CoFe₂O₄ samples were prepared in the form of powder by a simple sol–gel auto-combustion method from precursor solutions with different metal concentrations (0.1–0.3 mol L^?1) and pH values (<1–10). The samples were characterized by X-ray diffractometry, Fourier transform infrared spectrophotometry, transmission electron microscopy and N₂-physisorption. Their catalytic performances for oxidation of cyclohexane were evaluated using oxygen as oxidant in the absence of solvents. The results show that pH values and metal concentrations of precursor solutions play important roles in the sizes, dispersions and morphologies of the CoFe₂O₄ nanoparticles, and thus in their catalytic performances. The sample resulted from precursor solution under the conditions of pH = 7 and metal concentration = 0.1 mol L^?1 with the largest surface area, exhibited the best catalytic performance with the highest cyclohexane conversion of 13.7 % and selectivity of 93.9 % for cyclohexanol and cyclohexanone. The CoFe₂O₄ nanocrystal is also found an efficient catalyst for oxidation of aliphatic and aromatic alkenes.     

A simple method for the oxidation of α-amino acid esters to α-oximino esters

Magnesium bis(monoperoxyphthalate) hexahydrate (MMPP) was found to be an effective reagent for the oxidation of various α-amino acid esters to the corresponding α-oximino acid esters. This transformation could be completed under mild conditions within 2.5 h using 1.1 equiv of MMPP in THF. Clean oximino esters were obtained after quenching and extracting the reaction from sodium thiosulfate solution. The O-phosphorylated derivative of 2-oximinoglutarate exhibited slow binding inhibitory potency for the metallopeptidase prostate-specific membrane antigen (PSMA) with an IC₅₀ value of 58 nM.     

Oxidation of terpenoid diols with chlorine dioxide. Easy preparation of α-hydroxyketones

Oxidative dehydrogenation of vicinal diols of bornane and pinane type with chlorine dioxide in dimethylformamide has yielded α-hydroxyketones with high selectivity. 3α-Hydroxy-10β-pinane-4-one has been prepared for the first time with yield of 63–65%; the product structure has been confirmed by X-ray diffraction studies.     

Effect of preparation method on complexation of Cefdinir with β-cyclodextrin

The inclusion behaviour of β-cyclodextrin (βCD) was studied toward Cefdinir (CEF) in order to enhance the solubility and dissolution rate, following cyclodextrin complexation. Drug cyclodextrin solid systems were prepared by conventional methods of kneading (KN), co-evaporation (CE), spray drying (SD) and with a novel approach of microwave irradiation (MWI). The formation of inclusion complexes with βCD in the solid state, were confirmed by Differential scanning calorimetry (DSC), Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) studies, and comparative studies on the in vitro dissolution of CEF were carried out. Characterization of binary system by DSC, FTIR and SEM indicated that SD and MWI method resulted in formation of true complexes. Binary systems showed significant increase in dissolution rate as compared to plain drug. Amongst the binary systems MWI products were prepared in least time with better yield and highest dissolution rate.     

High-yielding method for preparation of carbocyclic or N-containing heterocyclic β-keto esters using in situ activated sodium hydride in dimethyl sulphoxide

It was found that NaH suspension in DMSO was highly activated when reacted with an alcohol. The in situ generated NaH/alkoxide mixture permitted very rapid and complete deprotonation and acylation of various cyclic ketones with alkyl carbonates at ambient temperature. Activated NaH/alkoxide in DMSO is particularly effective in Dieckmann condensations, where it affords 5- and 6-membered carbocyclic or N-containing heterocyclic β-keto esters in high yields. A heterocyclic Dieckmann condensation was performed on a molar scale, demonstrating the scalability of the procedure. Besides, DMSO is non-toxic, relatively inexpensive and environmentally benign solvent.