Asymmetric synthesis of pipecolic acid derivatives using the aza-Diels-Alder reaction
作者:Patrick D. Bailey、George R. Brown、Pritiof Korber、Amanda Reed、Robert D. Wilson
DOI:10.1016/s0957-4166(00)80025-7
日期:1991.1
Imines of the type R-N=CHCO2Et can be coerced into undergoing a (4 + 2) cycloaddition with substituted dienes if the reaction is carried out in DMF in the presence of both water and acid; these reactions show extremely high regio- and diastereoselectivity. Use of the 1-phenylethyl group as a chiral auxiliary leads to moderate asymmetric induction (typical d.e. ca. 70%); moreover, the diastereoisomers are surprisingly easy to separate, giving a short general route to optically pure substituted pipecolic acid derivatives.
Stereoselective synthesis of pipecolic acid derivatives using aza-diels-alder reactions
作者:Patrick D. Bailey、Robert D. Wilson、George R. Brown
DOI:10.1016/s0040-4039(00)70675-7
日期:——
Pipecolic acid derivatives can be prepared by the aza-Diels-Alder reaction of dienes with the iminium salt derived from benzylamine and ethyl glyoxylate in DMF; the presence of a catalytic quantity of water is essential, and acyclic dienes react with high regio- and diastereoselectivity.