Two routes are presented for the conversion of d-diacetone glucose (5a) into a protected carbocyclic core of BMS-200475 (Entecavir). The reduction of two terminal epoxides with Cp2TiCl to form carbon radicals and their cyclizations with a terminal acetylene and an α,β-unsaturated ester lead ultimately to allylic alcohol 11a, a candidate for Mitsunobu coupling with guanine.
提出了两种途径将d-
双丙酮葡萄糖(5a)转化为BMS-200475(
恩替卡韦)的受保护碳环核心。用Cp 2 TiCl还原两个末端
环氧化物形成碳自由基,并用末端
乙炔和α,β-不饱和酯将其环化,最终导致烯丙基醇11a,即Mitsunobu与
鸟嘌呤偶联的候选物。