Abstract 2-Ethynyl-4, 4, 6-trimethyl-1, 3, 2-dioxaborinane (III) was prepared and characterized by infrared, proton NMR, and 11 B NMR spectroscopy. Qualitative hydrolysis studies indicate that (III) is less reactive than dimethyl acetyleneboronate. Catalytic hydrogenation of (III) to form the corresponding ethyl and vinyl analogs, and Diels-Alder adducts of (III) with hexachlorocyclopentadiene and butadiene are reported.