Expedient Synthesis of Chiral 1,2- and 1,4-Diamines:  Protecting Group Dependent Regioselectivity in Direct Organocatalytic Asymmetric Mannich Reactions

[reaction: see text] Organocatalytic asymmetric Mannich reaction of protected amino ketones with imines in the presence of an L-proline-derived tetrazole catalyst afforded diamines with excellent yields and enantioselectivities of up to 99%. The amino ketone protecting group controlled the regioselectivity of the reaction providing access to chiral 1,2-diamines from azido ketones and 1,4-diamines from phthalimido ketones.