Substituted Dihydropyridine Synthesis by Dearomatization of Pyridines

Dearomatization is an effective method to transform readily available N‐heterocycles into partially saturated motifs. Manipulation of dihydro‐derivatives holds great potential and provides access to a variety of semi‐saturated N‐heterocyclic building blocks. However, current strategies are limited in scope and the use of sensitive reagents restricts the applicability in synthetic laboratories. Herein, we report the synthesis of a broad variety of N‐substituted 1,4‐ and 1,2‐dihydropyridines by very mild and selective reduction with amine borane for the first time.