Summary: B-trans-l-Alkenyl-9-borabicyclo [3.3. l] nonanes, easily and quantitatively prepared by the reaction of 9-BBN with various 1-alkynes in tetrahydrofuran, undergo facile reaction with a-halo carbanions generated from ethyl bromoacetate, phenacyl bromide, and chloroacetonitrile in the presence of potassium 2, 6-di-tert-butylphenoxide, providing the corresponding P, y-unsaturated esters, ketones, and nitriles in good yield.
