Copper-Catalyzed Electrophilic Amination of Oiorganozinc Reagents

摘要

From a preparative standpoint, this amination protocol has several attractive features. The reaction proceeds at ambient temperature in less than 1 h for all substrates tested. Isolation of analytically pure product via a simple acid/base extractive workup is suitable in most instances. The successful use of diorganozinc reagents generated in situ from the corresponding Grignard or organolithium obviates the need for isolation and distillation of R_2Zn nucleophiles. The starting N,N-dialkyl O-acyl hydroxylamine electrophiles are easily prepared in one step by Ganem's method. These materials are crystalline solids that show good stability: they can be purified via column chromatography and stored for months in a freezer with no evidence of decomposition or loss of reactivity. The copper-catalyzed electrophilic amination of diorganozincs offers a general, convenient, and high-yielding means of preparing tertiary amines under mild conditions. Catalytic delivery of R_2N-(+) synthons is a topic of continuing interest in our laboratory, and findings from this research will be the subject of future publications.