New tetrahedral boron heterobicycles: Cyclocondensation of phenylboronic acid with β-keto butanoic acid N-acyl hydrazones

Abstract

A series of 4-phenyl-2-aryl-8-methyl-6-oxo-7-phenylhydrazo-2H,4H,6H,7H,8H[1,3,4,2]-oxadiazaborolo[2,3-b][1,3,2]oxazaborines were prepared in high yields via the reaction of phenylboronic acid with various N-acylhydrazones of 3-keto-2-(2′-phenylhydrazono) butanoic acid in the presence of 4Å molecular sieves. These derivatives represent a novel class of zwitterionic, tetrahedral boron heterocycles. Single crystal X-ray analysis of a representative boron containing product is reported.