B(C6F5)3-catalyzed regio- and stereoselective cyanation of isatogens and their derivatives

Herein we report the regioselective cyanation of isatogen (3-indolone N-oxide) and its derivatives. The high electrophilicity of isatogen is a key feature for their various chemical transformations, and we describe a new application to use boron catalyst for regio- and stereoselective cyanation at C2 position of isatogen. The combination of B(C6F5)3 and Me3SiCN is optimal, and the C2-cyano adducts are exclusively obtained in up to quantitative yield. In addition, isatogenol that includes a tertiary hydroxyl group at C3 position is also suitable for this cyanation to create consecutive tetra-substituted carbons with high stereoselectivity.