Utility of the N-silyl enamines for organic synthesis

초록

N-silyl enamine is a fragile but potentially versatile functional group in organic chemistry. Due to the instability of the N-Si bond, the endocyclic N-silyl enamines had never been utilized for the organic synthesis until recent year. However, our group recently developed a synthetic methodology to achieve cyclic amidines via in-situ utilization of the endocyclic N-silyl enamines from dearomatization of the Nheteroarenes.1,2 Studies on reactivity and selectivity along with the different reaction mechanism of each N-heterocycle will be discussed. In the same vein, I will present our recent studies on the reactivity of the endocyclic N-silyl enamines with the activated acyl azides3 and the azomethine imines.4 Especially, the (3 + 2) cycloaddition of the N,N-cyclic azomethine imine and the N-silyl enamines showed interesting endo/exo selectivity according to the structure of N-silyl enamines and the 1,3-dipoles. An unexpected reaction pathway of the linear N,N-disilyl enamines will be followed with the preliminary applications.