A catalytic strategy was developed for asymmetric substitution reactions at sp3-hybridized carbon atoms by using a chiral alkylating agent generated in situ from trichloroacetimidate and a chiral phosphoric acid. The resulting chiral p-methoxybenzyl phosphate selectively reacts with β-amino alcohols rather than those without a β-NH functionality. The use of an electronically and sterically tuned chiral phosphoric acid enables the kinetic resolution of amino alcohols through p-methoxybenzylation with good enantioselectivity.