Unexpected double α,β-addition of secondary phosphine chalcogenides to 3-phenyl-2-propynenitrile

Bis(2-phenylethyl)phosphine oxide and sulfide react with 3-phenyl-2-propynenitrile in the presence of KOH under mild conditions to form unexpectedly alpha,beta-diadducts, 2,3-bis[bis(2-phenylethyl)phosphoryl]- and 2,3-bis[bis(2-phenylethyl)phosphorothioyl]-3-phenylpropionitriles.