Studies on the asymmetric cycloaddition of 2-azaallyl anions with alkenes
摘要:
A preliminary survey of strategies for the asymmetric cycloaddition of nonstabilized 2-azaallyllithiums with alkenes is reported. The chiral diamine (-)-sparteine exerted little, if any, absolute stereocontrol. The attachment of a chiral auxiliary to the anion was more successful, leading to the first example of an asymmetric cycloaddition of a 2-azaallyllithium (24 to 25, 98% e.e.). (C) 2001 Elsevier Science Ltd. All rights reserved.