Lanthanide/B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Promoted Hydroboration Reduction of Indoles and Quinolines with Pinacolborane
Jianping Zhang, Ziyan Chen, Mingxin Chen, Qi Zhou, Rongrong Zhou, Wenli Wang, Yinlin Shao, Fangjun Zhang
Abstract
We have developed a lanthanide/B(C 6 F 5 ) 3 -promoted hydroboration reduction of indoles and quinolines with pinacolborane (HBpin). This reaction provides streamlined access to a range of nitrogen-containing compounds in moderate to excellent yields. Large-scale synthesis and further transformations to bioactive compounds indicate that the method has potential practical applications. Preliminary mechanistic studies suggest that amine additives promote the formation of indole-borane intermediates, and the lanthanide/B(C 6 F 5 ) 3 -promoted hydroboration reduction proceeds via hydroboration of indole-borane intermediates with HBpin and in situ-formed BH 3 species, followed by the protodeborylation process.