Asymmetric Addition of Chiral 1,3,2-Benzoxazaphosphinine 2-Oxides to Aldehydes: Diastereoselective Synthesis of α-Substituted β-Hydroxyphosphonic Acids
作者:Beatriz López、Alicia Maestro、Rafael Pedrosa
DOI:10.1002/ejoc.200601102
日期:2007.6
The addition of stabilized phosphorus anions to aldehydes leads to α-substituted β-hydroxyphosphonates. The diastereoselectivity of the process is strongly influenced by the substitution of the phosphorus atom. Whereas P-ethyl derivatives provide a mixture of three isomers, the presence of a benzyl group enhances the stereocontrol, providing two diastereomers in ratios of up to 5:1. Elimination of
Diastereoselective Yang Photocyclization Reactions in Solution. Synthesis of Enantiopure Azetidin-3-ol Derivatives
作者:Rafael Pedrosa、Celia Andrés、Javier Nieto、Soledad del Pozo
DOI:10.1021/jo0481497
日期:2005.2.1
Chiral 2-acyl-3-allyl- or 2-acyl-3-benzyl-substituted perhydro-1,3-benzoxazines readily cyclized under irradiation to azetidin-3-ol derivatives. The diastereoselectivity of the cyclization is dependent on the nature of the substituents at the nitrogen atom. N-allyl-substituted derivatives yielded only two of the four possible diastereomers in moderate to good diastereomeric excess. The cyclization