Synthesis and characterization of new (N→B) phenyl substituted[N-benzyliminodiacetate-O,O',N]boranes

The synthesis of nine (N -> B) phenyl substituted[N-benzyliminodiacetate-O, O', N] boranes 3a-3i is reported herein. These compounds were characterized by H-1, C-13, B-11, HETCOR, NOESY, infrared spectroscopy, mass spectrometry and in the case of compounds 3d and 3g also by F-19 NMR. All compounds exhibit a bicyclic structure due to the presence of an intramolecular N. B coordination bond. The structure of 4-chlorophenyl[N-benzyliminodiacetate-O, O', N] borane 3e was further established by a single crystal x-ray diffraction study. The correlation between d(B-11) of compounds 3a, 3d-3i and sigma(Hammett) values shows that the strength of the N. B bond depends on the electronic factors of the substituent on the B-phenyl group.