Department of Chemistry, Princeton University , Princeton, New Jersey 08544, United States.
J Am Chem Soc. 2013 Dec 26;135(51):19107-10. doi: 10.1021/ja4108148. Epub 2013 Dec 16.
Bis(imino)pyridine cobalt methyl complexes are active for the catalytic hydroboration of terminal, geminal, disubstituted internal, tri- and tetrasubstituted alkenes using pinacolborane (HBPin). The most active cobalt catalyst was obtained by introducing a pyrrolidinyl substituent into the 4-position of the bis(imino)pyridine chelate, enabling the facile hydroboration of sterically hindered substrates such as 1-methylcyclohexene, α-pinene, and 2,3-dimethyl-2-butene. Notably, these hydroboration reactions proceed with high activity and anti-Markovnikov selectivity in neat substrates at 23 °C. With internal olefins, the cobalt catalyst places the boron substituent exclusively at the terminal positions of an alkyl chain, providing a convenient method for hydrofunctionalization of remote C-H bonds.
双(亚胺基)吡啶钴甲基配合物可用于催化末端、偕二、二取代的内烯烃、三取代和四取代烯烃与频哪醇硼烷（HBPin）的硼氢化反应。最活跃的钴催化剂是通过在双(亚胺基)吡啶螯合物的 4-位引入吡咯烷基取代基而得到的，这使得空间位阻较大的底物如 1-甲基环己烯、α-蒎烯和 2,3-二甲基-2-丁烯的硼氢化反应变得容易进行。值得注意的是，这些硼氢化反应在 23°C 下在纯底物中以高活性和反马氏选择性进行。对于内部烯烃，钴催化剂将硼取代基仅置于烷基链的末端位置，为远程 C-H 键的氢官能化提供了一种方便的方法。
