All Non-Carbon B3NO2 Exotic Heterocycle: Synthesis, Dynamics, and Catalysis.

The B3NO2 six-membered heterocycle (1,3-dioxa-5-aza-2,4,6-triborinane: DATB), comprising of three different non-carbon second-row elements, was recently demonstrated to be a powerful catalyst for dehydrative condensation of carboxylic acids and amines. The tedious synthesis of DATB, however, significantly diminished its utility as a catalyst, and thus the inherent chemical properties of the ring system remained virtually unexplored. Herein we disclose a general and facile synthetic strategy that harnesses a pyrimidine-containing scaffold for the reliable installation of boron atoms, giving rise to a series of Pym-DATBs from inexpensive materials in a modular fashion. The identification of a soluble Pym-DATB derivative allowed us to examine the dynamic nature of the B3NO2 ring system, revealing differential ring-closing and opening behavior depending on the medium. Readily accessible Pym-DATBs proved their utility as efficient catalysts for dehydrative amidation with broad substrate generality and functional group tolerance, offering a general and practical catalytic alternative to reagent-driven amidation.