Studies on the stereoselective selenolactonization, hydroxy and methoxy selenenylation of α- and β-hydroxy acids and esters. Synthesis of δ- and γ-lactones
作者:Carmela Aprile、Michelangelo Gruttadauria、Maria E Amato、Francesca D'Anna、Paolo Lo Meo、Serena Riela、Renato Noto
DOI:10.1016/s0040-4020(03)00206-0
日期:2003.3
The diastereoselective synthesis of hydroxy substituted γ- and δ-lactones was accomplished following two approaches. A 5- or 6-endo cyclization promoted by electrophilic selenium reagents of α- or β-hydroxyacids and a 5- or 6-exo cyclization of hydroxy esters obtained through a diastereoselective hydroxy selenenylation reaction of α- or β-hydroxy esters. Moreover, the diastereoselective methoxy selenenylation
Preparation of enantiomerically pure (3E)-alkyl-4-(hetero-2-yl)-2-hydroxybut-3-enoates by Candida parapsilosis ATCC 7330 mediated deracemisation and determination of the absolute configuration of (3E)-ethyl-4-(thiophene-2-yl)-2-hydroxybut-3-enoate
作者:T. Vaijayanthi、Anju Chadha
DOI:10.1016/j.tetasy.2007.04.029
日期:2007.5
enoates using Candida parapsilosis ATCC 7330 resulted in the formation of one enantiomer in high enantiomeric excess [up to >99% ee] and isolated yields [up to 79%]. The absolute configuration of the enantiomerically pure (3E)-ethyl-4-(thiophene-2-yl)-2-hydroxybut-3-enoate as determined by 1H NMR of the Mosher esters was found to be (S).
使用假丝酵母假丝酵母ATCC 7330对消旋的(3 E)-烷基-4-(杂-2-基)-2-羟基丁-3-烯酸酯进行消旋,导致形成一种对映体,其对映体过量高[ee高达> 99% ]和孤立的收率[高达79%]。通过Mosher酯的1 H NMR测定,发现对映体纯的(3 E)-乙基-4-(噻吩-2-基)-2-羟基丁-3-烯酸酯的绝对构型为(S)。