The 5-nitrosalicylate ester of 2-acetamidophenylboronic acid (C 15 H 10 BN 2 O 6) is formed under crystallization conditions from the 5-nitrosalicylate ester of 2-aminophenylboronic acid. The boron at the center of this structure exists as a tetrahedral complex produced by a dative bond with the amide carbonyl. The perpendicular shape produces an unusual packing structure including a bifurcated hydrogen bond between the amide hydrogen and carbonyl groups on two neighboring molecules. We propose that this reaction occurs due to increased Lewis acidity of the nitrosalicylate ester of 2-aminophenylboronic acid.
Levonis, S. M., Pappin, B. B., Healy, P. C., Kiefel, M. J., Simone, M., & Houston, T. A. (2017). Crystallization-induced amide bond formation creates a boron-centered spirocyclic system. Heterocyclic Communications, 23(3), 167-169. https://doi.org/10.1515/hc-2017-0023