Expeditive synthesis of homochiral fused tri- and tetrazoles–piperazines from β-amino alcohols

N-Cyanomethyl and N-propargyl β-amino alcohols are chlorinated with SOCl2 and treated with NaN3 in DMSO. A substitution/cycloaddition process affords in good yields, with high diastereoselectivity and a regioselectivity depending on the substitution pattern of the starting amino alcohol, fused tri- and tetrazoles–piperazines. These heterocycles were further lithiated with n-BuLi at the benzylic position and reacted diastereoselectively with a range of electrophiles.