Solvent-Tuned Selective N -Ethylation and N -Acetylation of Amines Using NaBH(OAc) 3

We herein describe an efficient and highly selective N-ethylation and N-acetylation of secondary amines using sodium triacetoxyborohydride NaBH(OAc)3 as alkyl and acetyl sources, which were controlled by the solvent. High isolated yields were obtained for a series of N-substituted amine substrates with flash column chromatographic purification. The practicability of the methodology was demonstrated by synthesizing an approved drug, and the mechanism was proposed based on experiments.