P-C Bond Cleavage by Hydroxyl Function during the Addition of Tris(2-pyridyl)phosphine to Cyanopropargylic Alcohols in Water

The addition of tris(2-pyridyl)phosphine to tertiary cyanopropargylic alсоhols in water (room temperature, no catalyst, 5 h) is accompanied by elimination of pyridine to give cyanoallyldipyridylphosphinates of E-configuration in 60–73% yield, thus indicating the oxygen insertion of the hydroxyl group into the PC bond of the intermediate (Z)-alkenyldipyridylphosphine oxide.