Crabée interrupted: Propargylamines 1 react with α-isocyanoacetamides 2 in the presence of zinc bromide to afford vinyl oxazoles 3. The transformation, wherein the propargylamine acts as a vinyl cation synthetic equivalent, involves a domino sequence incorporating a 1,5-hydride shift, intermolecular trapping/cyclization, and a 1,6-elimination (see scheme).
                                    螃蟹被打断:在
溴化锌存在下,
炔丙胺1与α-异
氰基乙酰胺2反应得到
乙烯基恶唑3。该转化(其中
炔丙基胺充当
乙烯基阳离子合成等价物)涉及一个结合了1,5-
氢化物移位的多米诺序列,分子间的捕获/环化和1,6-消除(参见方案)。