Asymmetric Synthesis of β-Mercapto Carboxylic Acid Derivatives by Intramolecular Sulfur Transfer in <i>N</i>-Enoyl Oxazolidine-2-thiones Promoted by Lewis Acids
Oxazolidine-2-thiones and Thiazolidine-2-thiones as Nucleophiles in Intermolecular Michael Additions
作者:Laura Munive、Veronica M. Rivas、Aurelio Ortiz、Horacio F. Olivo
DOI:10.1021/ol301489y
日期:2012.7.6
Conjugate addition of thiazolidinethiones and oxazolidinethiones to N-crotonylthiazolidinethiones and -oxazolidinethiones was observed in the presence of excess triethylamine in dichloromethane. The addition takes place by the nitrogen of the heterocycle with high diastereoselectivity. It was observed that the stereoselective addition occurs on the anti-s-cis conformation of the N-enoyl sulfur-containing heterocycle.
Stereochemical control on the Michael addition of chiral 1,3-oxazolidine-2-thiones to N-crotonyl 1,3-oxazolidin-2-ones
作者:Laura Munive、Sena A. Dzakuma、Horacio F. Olivo
DOI:10.1016/j.tetlet.2012.12.074
日期:2013.3
Addition of both antipodes of 4-phenyl 1,3-oxazolidine-2-thione to 4-substituted N-crotonyl 1,3-oxazolidin-2-ones furnished Michael addition products. A perfect match occurred when both Michael donor and acceptor possessed the same stereochemistry and a mismatch when they had opposite stereochemistries. The newly created stereochemical center was shown to be governed by the Michael donor and not by the acceptor. (C) 2012 Elsevier Ltd. All rights reserved.