Borole formation by 1,1-carboboration.

Bis(trimethylsilylethynyl)diphenylaminoborane was reacted with the strong Lewis acid B(C6F5)3 at ambient temperature to give the borole 9 admixed with a small amount of its thermal follow-up product 12. Compound 9 was subsequently stabilized by adduct formation with pyridine (10). Treatment of bis(trimethylsilylethynyl)phenylborane with B(C6F5)3 gave the borole 14, which reacted with 3-hexyne to give the [4 + 2] cycloaddition product 15.