Difunctionalization of ketones <i>via gem</i>-bis(boronates) to synthesize quaternary carbon with high selectivity
作者:Purui Zheng、Yujie Zhai、Xiaoming Zhao、Tao XU
DOI:10.1039/c8cc07781a
日期:——
quaternary centres from ketones via the diborylation process and Suzuki–Miyaura cross-coupling reaction. This methodology, which simultaneously introduces two different kinds of electrophilic structures, exhibits a large substrate scope and high functional group tolerance. The reaction products with aldehyde and allylic groups have proved to be versatile synthons to prepare complex molecules crucial for natural
Enantiomerically enriched beta-(diphenylphosphatoxy)nitroalkanes undergo radical ionic fragmentation, induced by tributyltin hydride and AIBN in benzene at reflux, to give alkene radical cations in contact radical ion pairs. These contact ion pairs are trapped intramolecularly by amines to give pyrrolldines and piperidines with significant enantloselectivity (similar to60% ee), indicative of cyclization competing effectively with equilibration within the ion pairs. Use of an intramolecular N-propargylamine as a nucleophile provides an enantiomerically enriched pyrrolizidine skeleton via a tandem polar/radical crossover sequence.