A conceptually novel reaction cascade is presented, which allows readily available enynes to be converted into functionalized 1,3‐dienes comprising a stereodefined tetrasubstituted alkene unit; such compounds are difficult to make by conventional means. The overall transformation is thought to commence with formation of a metallacyclic intermediate that evolves via cleavage of an unstrained C−X bond in its backbone. This non‐canonical cycloisomerization process is followed by a cross‐coupling step, such that reductive C−C bond formation regenerates the necessary low‐valent metal fragment and hence closes an intricate catalytic cycle. The cascade entails the formation of two new C−C bonds at the expense of the constitutional C−X entity of the substrate: importantly, the extruded group X must not be a heteroelement (X=O, NR), since activated β‐C−C bonds can also be broken. This concern was reduced to practice in two largely complementary formats: one procedure relies on the use of alkyl‐Grignard reagents in combination with catalytic amounts of Fe(acac)_3, whereas the second method amalgamates cycloisomerization with Suzuki coupling by recourse to arylboronic acids and phosphine‐ligated palladium catalysts.

中文翻译：

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铁或钯催化的级联反应与环化和交叉偶联化学融合

提出了一种概念上新颖的反应级联反应，该反应级联可以将现成的烯炔转化为包含立体定义的四取代烯烃单元的功能化1,3-二烯；这样的化合物很难通过常规方法制备。一般认为，整个转变始于金属环中间体的形成，该金属环中间体通过其骨架中未应变的C-X键的裂解而进化。这种非规范的环异构化过程之后是交叉偶联步骤，从而还原性C-C键的形成可再生必要的低价金属片段，从而关闭复杂的催化循环。级联需要两个新的C-C键的形成，但会损害底物的结构C-X实体：重要的是，挤出的基团X一定不能是杂原子（X = O，NR），因为活化的β-C键也可以被破坏。这种担忧已减少为以两种主要互补的形式进行实践：一种程序依赖于使用烷基格利雅试剂与催化量的Fe（acac）结合使用参见图_3，而第二种方法是通过使用芳基硼酸和膦连接的钯催化剂与Suzuki偶联使环异构化合并。