High Kinetic Resolution in the Addition of a Racemic Allenylzinc onto Enantiopure <i>N</i>-<i>tert</i>-Butanesulfinimines: Concise Synthesis of Enantiopure <i>trans</i>-2-Ethynylaziridines<sup>1</sup>
作者:Fabrice Chemla、Franck Ferreira
DOI:10.1021/jo0490696
日期:2004.11.1
Enantiopure trans-ethynyl N-tert-butanesulfinylaziridines (R-s)-6 were prepared in good to excellent yields by the condensation of the racemic allenylzinc species 1 derived from 3-chloro-l-trimethyl-silylpropyne onto the corresponding enantiopure N-tert-butanesulfinimines (R-s)-5. The absolute stereochemistry of enantiopure N-tert-butanesulfinylaziridines (R-s)-6 was shown to be (R-s,2R,3R) and results from a chelate-type transition state in which the zinc atom of allenylzinc 1 is coordinated by both the nitogen and the oxygen atoms of the imine. Further removal of the N-tert-butanesulfinyl auxiliary of alkyl 3-substituted and 3,3-disubstituted ethynyl N-tert-butanesulfinylaziridines (Rs)-6 could be achieved by treatment with HCl in MeOH affording the corresponding deprotected aziridines (2R,3R)-9 and (2R)-9 respectively as enantiomerically pure compounds.
Efficient Synthesis of α-Quaternary α-Hydroxy-β-amino Esters via Silyl Glyoxylate-Mediated Three-Component Reactions
作者:Jiu-Long Jiang、Ming Yao、Chong-Dao Lu
DOI:10.1021/ol403388w
日期:2014.1.3
An efficient method has been developed for the enantioselective synthesis of fully protected alpha-quaternary alpha-hydroxy-beta-amino esters via the coupling of three components: aryl Grignard reagents (or methyllithium), silyl glyoxylate, and N-tert-butanesulfinyl imines. This protocol enables successive formation of two C-C bonds and two adjacent chiral carbons with high stereocontrol in a one-pot operation.