Highly Enantiospecific Borylation for Chiral α‐Amino Tertiary Boronic Esters.

Herein we report a highly efficient and enantiospecific borylation method to synthesize a wide range of enantiopure (>99 % ee) α‐amino tertiary boronic esters. The configurationally stable α‐N‐Boc substituted tertiary organolithium species and pinacolborane (HBpin) underwent enantiospecific borylation at −78 °C with the formation of a new stereogenic C−B bond. This reaction has a broad scope, enabling the synthesis of various α‐amino tertiary boronic esters in excellent yields and, importantly, with universally excellent enantiospecificity (>99 % es) and complete retention of configuration. [ABSTRACT FROM AUTHOR]