Stereodefined Synthesis of a New Type of 1,3-Dienes by Ligand-Controlled Carbon−Carbon and Carbon−Heteroatom Bond Formation in Nickel-Catalyzed Reaction of Diaryldichalcogenides with Alkynes

We have found that ligand control over the carbon−carbon and carbon−heteroatom bond formation on the nickel center provides an easy and convenient route to symmetrical (minor) and unsymmetrical (major) isomers of sulfur- and selenium-substituted 1,3-dienes. The unsymmetrical product is a new type of 1,4-substituted conjugated diene, which was readily synthesized from alkynes and diaryldichalcogenides. The unique feature of this developed one-pot transformation is total stereodefined synthesis of the diene skeleton, controlling not only the configuration of the double bond but also the s-gauche conformation of the central C−C bond. The mechanistic study revealed the key feature of alkyne insertion into the Ni−E and Ni−C bonds (E = S, Se), which governs the direction of the chemical transformation.本研究发现，配体对镍中心上碳-碳键及碳-杂原子键形成的调控，为合成硫代及硒代1,3-二烯的对称（次级）和不对称（主级）异构体提供了一种简便且便捷的途径。不对称产物是一种新型的1,4-取代共轭二烯，可由炔烃与二芳基二卤化物轻松合成。所开发的单步转化过程具有独特的特性，实现了二烯骨架的完全立体定义合成，不仅控制了双键的构型，还调控了中心C-C键的s-顺式构象。机理研究表明，炔烃插入到Ni-E和Ni-C键（E = S, Se）中的关键特征，决定了化学转化的方向。