The formation in high yields of various substituted allenes by the reaction of triethylborane with alkynyl stannanes is reported. NMR data (1H, 11B, 13C, 119Sn) of the allenes and of their derivatives prepared by the reaction of the allenes with acetic acid prove the proposed structures.
inhibited by sodium hydroxide. Acetic acid, however, removes the first ethyl group rapidly, followed by a slower removal of the second. The protonolysis of the third ethyl group requires elevated temperatures. The unusual reactivity of carboxylic acid toward protonolysis of triethylborane is attributed to the presence of both acidic and basic sites in close proximity. The effect of added reagents is also