Reaction of the lithio-derivative of methoxyallene with hydrazones. Part 2: Formation of 3-pyrrolines and azetidines; synthetic and mechanistic aspects
作者:Valérie Breuil-Desvergnes、Jacques Goré
DOI:10.1016/s0040-4020(01)00031-x
日期:2001.3
3-pyrrolines when the time and temperature of the reaction are increased, but the rate of this transformation depends on the substituents of the terminal nitrogen. A reaction mechanism is proposed which involves intermolecular or intramolecular electron transfers from the lithium amide leading to hydrazinyl radicals. The relative stabilities of these intermediates may then explain the role of the substituents
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.