Department of Chemistry, Oregon State University, Corvallis, OR, 97330, USA.
Fachbereich Chemie der Philipps Universität Marburg, 35032, Marburg, Germany.
Angew Chem Int Ed Engl. 2018 Jan 8;57(2):390-407. doi: 10.1002/anie.201707026. Epub 2017 Nov 15.
Two carbenoids combine to generate an olefin by a mechanism involving formation of an ate complex, 1,2-metalate rearrangement, and β-elimination. As each stage of this eliminative coupling is stereospecific, the overall stereochemical outcome can be understood and, in principle fully controlled, providing that the absolute stereochemical configurations of the reacting carbenoid species are defined. In contrast to traditional alkene syntheses, the eliminative cross-coupling of carbenoids offers a connective approach to olefins capable of precisely targeting a given isomer regardless of the nature of the features distinguishing the isomers. The formation of olefins by the eliminative dimerization and eliminative cross-coupling of carbenoids is reviewed with a range of illustrative examples, including the reactions of α-lithiated haloalkanes, epoxides, and carbamates. An emphasis is placed on stereochemical analysis and methods to generate sp -hybridized carbenoids in stereodefined form are surveyed.
两个卡宾通过涉及形成ate 配合物、1,2-金属迁移重排和β-消除的机制结合生成烯烃。由于消除偶联的每个阶段都是立体特异性的，因此可以理解整体立体化学结果，并且原则上可以完全控制，只要反应性卡宾物种的绝对立体化学构型被定义。与传统的烯烃合成相比，卡宾的消除交叉偶联提供了一种连接方法来合成烯烃，能够精确靶向给定的异构体，而与区分异构体的特征的性质无关。本文综述了卡宾的消除二聚化和消除交叉偶联形成烯烃的反应，其中包括α-锂化卤代烷烃、环氧化物和氨基甲酸酯的反应。重点是立体化学分析和以立体确定的形式生成 sp 杂化卡宾的方法。
