Stereoselective Synthesis of α-Phosphorylated Spiranes

α-Oxospiranes have been converted into vinyl triflates for phosphorylation and arylation by palladium-catalyzed cross-coupling reactions. With diethyl phosphite, the coupling provided olefinic mono- and diphosphonated spiranes. Saturation of conjugated aryl and phosphonyl alkene bonds was stereoselective when effected by catalytic hydrogenation. The double bond in conjugated alkenylphosphonates was in general more difficult to reduce than conjugated aryl derivatives. In mixed substrates, regioselectivity in the saturation of conjugated olefinic bonds was obtained.