Abstract The B 3 NO 2 six‐membered heterocycle (1,3‐dioxa‐5‐aza‐2,4,6‐triborinane=DATB), comprising three different non‐carbon period 2 elements, has been recently demonstrated to be a powerful catalyst for dehydrative condensation of carboxylic acids and amines. The tedious synthesis of DATB, however, has significantly diminished its utility as a catalyst, and thus the inherent chemical properties of the ring system have remained virtually unexplored. Here, a general and facile synthetic strategy that harnesses a pyrimidine‐containing scaffold for the reliable installation of boron atoms is disclosed, giving rise to a series of Pym‐DATBs from inexpensive materials in a modular fashion. The identification of a soluble Pym‐DATB derivative allowed for the investigation of the dynamic nature of the B 3 NO 2 ring system, revealing differential ring‐closing and ‐opening behaviors depending on the medium. Readily accessible Pym‐DATBs proved their utility as efficient catalysts for dehydrative amidation with broad substrate scope and functional‐group tolerance, offering a general and practical catalytic alternative to reagent‐driven amidation.