efficiency of the oxazolidin-2-thione chiral auxiliary in the facial discrimination of Diels-Alder reactions. The absolute configuration of the 3,4,5-trisubstituted cyclohexene derivatives (3a-c) was established by X-ray diffraction analysis. NMR studies confirmed the relative stereochemistries and showed two possible conformers in solution. (C) 2007 Elsevier B.V. All rights reserved.
A theoretical model for the facial selectivity of N-dienyl oxazolidin-2-(thi)one and thiazolidin-2-thione 2a-c is presented. Our analysis provides a clear understanding of factors controlling stereoselectivity in reaction of these dienes, and allows predictions of high diastereoselectivity in the case of oxazolidin-2-thionyl diene (2b). The application of this diene to the synthesis of beta- and gamma-aminophosphonic derivatives is then investigated. Under classical conditions or under microwave activation, the D-A reaction of diene 2b leads to aminophosphonic chirons with high regio- and stereoselectivities. (C) 2009 Elsevier Ltd. All rights reserved.
Design of a New and Highly Effective Chiral Auxiliary for Diels−Alder Reaction of 1-Aminodiene
investigation of the facial selectivity of optically active oxazolidin-2-one-substituted dienes has been realized. This analysis enabled the development of (R)-4-phenyloxazolidin-2-thione as a very effectivechiralauxiliary for cycloaddition of 1-aminodiene.
Stereochemistry (absolute or relative) of four compounds have been established by x-ray diffraction analysis, namely: 3(R)-[4′(R)-(phenyl) oxazolidin-2-one-1-yl]-4(S)-dimethoxyphosphoryl-4-methoxycarbonyl-1-cyclohexene (7), 3(R)-[4′-(R)-(phenyl)-oxazolidin-2-thione-1-yl]-4(S)dimethoxyphosphoryl-4-methoxycarbonyl-1-cyclohexene (8), methyl 1dimethoxyphosphoryl-2-succinimido-3,4-epoxy-cyclohexane-1-carboxylate