Polar reactive organometallic species have been key reagents in synthesis for more than a century. Stereodefined 1,2-dimetallated alkenes offer promising synthetic utility; however, few methods are available for their preparation due to their relatively low stability. Here we report the reductive anti-1,2-dimetallation of alkynes to stereoselectively generate trans-1,2-dimagnesio- and 1,2-dialuminoalkenes, which are stable and have been demonstrated in organic synthesis. These stereodefined 1,2-dimetallated alkenes are prepared through the use of a sodium dispersion as a reducing agent, and organomagnesium and organoaluminium halides as reduction-resistant electrophiles. Highly nucleophilic 1,2-dimagnesioalkenes serve as dual Grignard reagents and have been demonstrated to react with various electrophiles to afford anti-difunctionalized alkenes. The 1,2-dialuminoalkenes react with paraformaldehyde with dearomatization of the aryl moieties to form the corresponding dearomatized 1,4-diols, with the overall reaction being regarded as alkynyl-directed dearomatization of arenes. X-ray crystallographic analysis further supports the formation of trans-1,2-dimagnesio- and 1,2-dialuminoalkenes, with computational studies providing insight into the mechanism of dearomative difunctionalization.

一个多世纪以来，极性活性有机金属物种一直是合成中的关键试剂。立体定义的 1,2-二金属烯烃提供了有前途的合成实用性；然而，由于其相对较低的稳定性，很少有方法可用于制备它们。在这里，我们报告了炔烃的还原反-1,2-二金属化以立体选择性地产生反式-1,2-dimagnesio- 和 1,2-dialuminoalkenes，它们是稳定的并且已在有机合成中得到证明。这些立体定义的 1,2-二金属化烯烃是通过使用钠分散体作为还原剂，有机镁和有机铝卤化物作为耐还原亲电子试剂制备的。高度亲核的 1,2-二镁烯烃用作双重格氏试剂，并已被证明可与各种亲电子试剂反应，得到反双官能化烯烃。1,2-二铝烯烃与多聚甲醛反应，芳基部分脱芳构化形成相应的脱芳构化的 1,4-二醇，整个反应被视为炔基定向的芳烃脱芳构化。X 射线晶体学分析进一步支持反式的形成-1,2-dimagnesio- 和 1,2-dialuminoalkenes，计算研究提供了对脱芳双功能化机制的洞察。