The synthesis of P-chiral compounds is challenging, especially since useful catalytic methods for preparing such molecules are scarce. Herein we disclose a desymmetrization that employs phosphinic acids as prochiral nucleophiles in a Pd-catalyzed asymmetric allylic alkylation reaction, furnishing phosphinates with high enantio- and diastereoselectivity. This new method has broad scope and is applied to the synthesis of an enantioenriched tertiary phosphine oxide.