A number of 3,5,6-tri- and 3,4,5,6-tetrasubstituted α-pyrones have been prepared in good yields by the reaction of vinylic iodides, bromides or triflates bearing ester functionality with internal alkynes in the presence of a palladium catalyst. The methodology provides an especially simple, convenient, and regioselective route to α-pyrones containing aryl, silyl, tert.-alkyl and other hindered groups
通过在存在下的条件下,通过将带有
酯官能团的
乙烯基碘化物,
溴化物或
三氟甲磺酸酯与内部
炔烃反应,可以高收率制备出许多3,5,6-三-和3,4,5,6-四取代的
α-吡喃酮。
钯催化剂。该方法为包含芳基,甲
硅烷基,叔烷基和其他受阻基团的
α-吡喃酮提供了特别简单,方便和区域选择性的途径。据信该反应通过七元的Paladacyclocyclic盐进行,其中反应的区域
化学由空间因素控制。