Highly stereoselective syntheses of conjugated , - and , -dienes, -enynes and -1,2,3-butatriened via alkenylborane derivatives

A highly selective and potentially general methodology for the synthesis of conjugated E,E- and E,Z-dienes, E-enynes, and E-1,2,3-butatrienes via hydroboration of alkynes is reported. The observed stereosclectivity was >98–99%.