An efficient synthesis of chiral dihydrooxazines from 1-aryl-2-amino-propane-1,3-diols via the corresponding bistrichloroacetimidate intermediates has been developed. In this transformation, one trichloroacetimidate acts as a leaving group and the other acts as a nucleophile. The cyclization proceeds through an SN1 mechanism to provide trans-dihydrooxazines with complete diastereoselectivity irresp. of the abs. configuration of the benzylic alc. The transformation of the chiral dihydrooxazines into other selectively protected aminodiols is also documented. [on SciFinder (R)]