Metal‐Free Directed C−H Borylation of Pyrroles
Zhengjun Wang, Xiangyang Chen, Lei Wu, Jonathan J. Wong, Yong Liang, Yue Zhao, K. N. Houk, Zhuangzhi Shi
Abstract
Abstract Robust strategies to enable the rapid construction of complex organoboronates in selective, practical, low‐cost, and environmentally friendly modes remain conspicuously underdeveloped. Here, we develop a general strategy for the site‐selective C−H borylation of pyrroles by using only BBr 3 directed by pivaloyl groups, avoiding the use of any metal. The site‐selectivity is generally dominated by chelation and electronic effects, thus forming diverse C2‐borylated pyrroles against the steric effect. The formed products can readily engage in downstream transformations, enabling a step‐economic process to access drugs such as Lipitor. DFT calculations (wB97X‐D) demonstrate the preferred positional selectivity of this reaction.