Selective [3 + 2] Huisgen cycloaddition. Synthesis of trans-disubstituted triazolodiazepines from aza-Baylis-Hillman adducts.

The 1,3-dipolar cycloaddition of linear azido alkynes derived from protected beta-amino esters proceeds via diastereomeric differentiation to provide trans-disubstituted triazolodiazepines in good yields.