13C NMR as a general tool for the assignment of absolute configuration
作者:Iria Louzao、José Manuel Seco、Emilio Quiñoá、Ricardo Riguera
DOI:10.1039/c0cc02774j
日期:——
(13)C NMR, alone or in combination with (1)H NMR, allows the assignment of the absolute configuration of chiral alcohols, amines, carboxylic acids, thiols, cyanohydrins, sec,sec-diols and sec,sec-aminoalcohols, derivatized with appropriate chiral auxiliaries. This extends the assignment possibilities of NMR to fully deuterated and to nonproton containing compounds.
Deracemization of (±)-2,3-disubstituted oxiranes via biocatalytic hydrolysis using bacterial epoxide hydrolases: kinetics of an enantioconvergent process
作者:Wolfgang Kroutil、Martin Mischitz、Kurt Faber
DOI:10.1039/a704812b
日期:——
Asymmetric biocatalytichydrolysis of (±)-2,3-disubstituted oxiranes leading to the formation of vicinal diols in up to 97% ee at 100% conversion was accomplished by using the epoxide hydrolase activity of various bacterial strains. The mechanism of this deracemization was elucidated by 18OH2-labelling experiments using a partially purified epoxide hydrolase from Nocardia EH1. The reaction was shown
Biocatalytichydrolysis of (±)-cis-2,3-epoxyheptaneusing lyophilized bacterial cells of Nocardia EH1 gave (2R,3R)-heptane-2,3-diol as the sole product in 79% yield and 91% e.e. at 100% conversion. The pathway of this deracemization was elucidated by 18OH2-labelling experiments using a partially purified epoxide hydrolase preparation and was shown to proceed in an enantioconvergent manner. Thus both
作者:Lu Yan、Yan Meng、Fredrik Haeffner、Robert M. Leon、Michael P. Crockett、James P. Morken
DOI:10.1021/jacs.7b12316
日期:2018.3.14
A mechanistic investigation of the carbohydrate/DBU cocatalyzed enantioselective diboration of alkenes is presented. These studies provide an understanding of the origin of stereoselectivity and also reveal a strategy for enhancing reactivity and broadening the substrate scope.
Iron-Catalyzed Asymmetric Olefincis-Dihydroxylation with 97 % Enantiomeric Excess