[3-(Diphenylphosphino)allyl] titanium reagent generated easily from allyldiphenylphosphine condenses with aldehydes to give ()-1,3-alkadienes in a highly regio- and stereoselective manner. In contrast, lithiated allyldiphenylphosphine oxide condenses with aldehydes to give ()-1,3-alkadienes directly and stereoselectively in good yield. Similarly, lithiated (1-buten-3-yl)diphenylphosphine oxide condenses