Alkenylation of thiophenes and furans at the 2-position and a synthesis of allenes conjugated with α,β-unsaturated ester with magnesium alkylidene carbenoids
作者:Natsuki Mori、Kazumi Obuchi、Takashi Katae、Jo Sakurada、Tsuyoshi Satoh
DOI:10.1016/j.tet.2009.02.019
日期:2009.4
to afford thiophenes and furans bearing a fully substituted alkene at the 2-position. Treatment of the magnesium alkylidene carbenoids with 2-lithio-5-methoxyfuran afforded allenes conjugated with α,β-unsaturated methyl ester in moderate yields. These procedures offer a new and versatile one-pot synthesis of 2-alkenylthiophenes, 2-alkenylfurans, and allenes conjugated with α,β-unsaturated methyl ester
1-氯乙烯基反应p -甲苯基砜,由酮和氯衍生p -甲苯基砜,与我-PrMgCl在-78°C下得到亚烷基镁类胡萝卜素。用2-硫代噻吩和2-硫代呋喃处理镁类胡萝卜素分别以高到高的产率形成了2-烯基化的噻吩和呋喃。发现这些反应的中间体是烯基镁,其可以被几种亲电试剂捕集,得到噻吩和呋喃,其在2-位带有完全取代的烯烃。用2-硫代-5-甲氧基呋喃处理亚烷基镁的类胡萝卜素,以中等收率得到了与α,β-不饱和甲基酯共轭的烯丙基。这些方法提供了一种新的通用的一锅法合成的方法,可从1-氯乙烯基对甲苯基亚砜中合成2-烯基噻吩,2-烯基呋喃和与α,β-不饱和甲酯共轭的丙二烯。