Competing cyclopropane over epoxide formation from γ-halogeno-δ-hydroxy-ketones

Carbocyclization has been selectively achieved over epoxide formation from a γ-chloro-δ-hydroxy-ketone in the presence of a lithiumamide or using a different strategy in which the related silyloxyenol ether bearing an iodine atom at gamma-position and a silyloxy group in delta-position is reacted with tetrabutylammonium fluoride. These approaches take advantage of (i) the poor reactivity of the intermediate β-halogeno lithiumalkoxide first formed in the former case and (ii) the poorer ability of the fluoride ion to desilylate a silyl ether over a silylenol ether.     

Regioselective ring opening of epoxides using NH4SCN/silica sulfuric acid: An efficient approach for the synthesis of β-hydroxy thiocyanate under solvent-free conditions

Silica sulfuric acid was developed as a stable and efficient heterogeneous catalyst in organic synthesis. This solid acid catalyzed the regioselective ring opening of epoxides by thiocyanate anion to give thiocyanohydrins as key intermediates in agricultural and pharmaceutical chemistry in high yields under solvent-free conditions.     

Reaction of Epoxides with (Alkylthio)methyl Chloride

The reaction of (methylthio)methylchloride with 1,2-epoxybutane and styrene oxide furnishes eleven and eight compounds, respectively. The probable mechanism of their formation and their mass spectral characterization are presented in this article.     

Biocatalytic Resolution of para‐Nitrostyrene Oxide by Resting Cells of Different Aspergillus niger Strains

Biocatalytic resolution of racemic para‐nitrostyrene oxide was accomplished by employing the epoxide hydrolases from the whole cells of several Aspergillus niger (A. niger) strains. In the cases investigated, excellent selectivity was achieved with such strains as A. niger 5450, A. niger 5320.     

Steric effects in the tetracyanoethylene catalysed methanolysis of some cyclohexane epoxides

The presence of a hydroxyl group has been shown to direct the regiochemistry and stereochemistry of the TCNE methanolysis of cyclohexane hydroxy-epoxides. α-Pinene epoxide underwent cleavage to form the 8-methyl ether of trans-sobrerol.     

DICHLORO (5,10,15,20-TETRAPHENYLPORPHYRIN) PHOSPHORUS(V) CHLORIDE AS A NEW CATALYST FOR CONVERSION OF 1,2-EPOXYETHANES TO 2-HYDROXYETHYL THIOCYANATES WITH AMMONIUM THIOCYANATE

A convenient and efficient procedure for the cleavage of the oxirane rings with ammonium thiocyanate in the presence of phosphorus(V)tetraphenylporphyrin is described. The ring-opening of 1,2- epoxyethanes is found to proceed regioselectively under mild reaction conditions. Thus, several 2-hydroxyethyl thiocyanates, useful intermediates toward biologically active molecules, are easily obtained in very good yields.     

Highly regio- and stereoselective ring-opening of epoxides and aziridines with sodium azide using ammonium-12-molybdophosphate

Epoxides and aziridines undergo ring-opening readily with NaN₃ in the presence of ammonium-12-molybdophosphate to afford the corresponding 2-azidoalcohols and 2-azidoamines in high yields with good regio- and stereoselectivity under mild reaction conditions.     

分光光度法测定环氧化物浓度与环氧化物水解酶活性

研究了在弱碱性条件下 ,利用环氧化物与 4- (对硝基 )苄基吡啶之间的显色反应测定环氧化物含量 ,进而计算环氧化物水解酶活性的分光光度法。对于缩水甘油苯基醚 ,其最低检出浓度为 4.5 μmol/L,所生成染料的摩尔吸光系数 ε为 2 .2 0× 1 0 3L· mol- 1· cm- 1。在 4.5～ 30 0 μmol/L的浓度范围内 ,测量的精密度可达 0 .9%。     

Direct conversion of epoxides to vic-difluorides

vic-Difluoro compounds can be directly prepared from epoxides by reaction with Et₃N-3HF and DFMBA under microwave-irradiation conditions.