Base Promoted Hydrogenation of N-Heteroarenes with Ammonia Borane and DMSO

Herein, we report a sodium tert-butoxide-promoted reduction of N-heteroarenes using ammonia borane and dimethyl sulfoxide (DMSO) under mild reaction conditions. This method demonstrates broad functional group compatibility across diverse N-heteroarene substrates. Notably, substituting DMSO with deuterated DMSO-d₆ enables the synthesis of C3-deuterated 1,2,3,4-tetrahydroquinolines with remarkable positional selectivity. Mechanistic investigations indicate that the protons are derived from both ammonia borane and DMSO. This strategy establishes a novel and environmentally benign approach for the synthesis of (deuterated) N-heterocycles, offering practical advantages in terms of operational simplicity and sustainable reaction conditions.