alpha-Lithio methoxy allene reacts with SAMP-hydrazones to give alpha-allenyl hydrazines 5 or 3-methoxy-3-pyrrolines 6 depending on the nature of the solvent. Both compounds have been obtained with d.e. greater than or equal to 99%. Hydrogenolysis of the N-N bond of 6 affords the pyrroline 7 in enantiopure form. (C) 1999 Elsevier Science Ltd. All rights reserved.
Reaction of the lithio-derivative of methoxyallene with hydrazones. Part 1: Synthesis and transformation of α-allenyl hydrazines
作者:Valérie Breuil-Desvergnes、Jacques Goré
DOI:10.1016/s0040-4020(01)00030-8
日期:2001.3
methoxyallene reacts with aldehyde hydrazones leading to expected α-allenyl hydrazines when ether is the solvent of the reaction. The yields are good as well as the diastereoselectivity observed in the case of SAMP-hydrazones. These hydrazines are cleanly transformed to N-dialkylamino-3-methoxy-3-pyrrolines when they are reacted with n-BuLi in THF. These compounds are sometimes accompanied by the isomeric