Hydrolytically Stable Tricoordinate Chiral Bicyclo[4.4.0]diboronic Ester: Synthesis, Structural Characterization, and Theoretical Investigation^†

The hydrolytically and thermally stable tricoordinate chiral bicyclo[4.4.0] diboronic ester (R,R)-3c was synthesized via a one-step reaction of a Grignard reagent with chiral spiroborate esters (R,R,S)-1 and (R,R)-2. Its structure was characterized by its IR, 1H, 13C, and 11B NMR, and mass spectra and confirmed by X-ray analysis. Further theoretical investigation of the three possible bicyclic structures corresponding to the formula C40H32B2O4 was performed at different levels of theory. Excellent agreement with the X-ray result was obtained.