Synthesis of Unsaturated N-Heterocycles by Cycloadditions of Aziridines and Alkynes

Abstract

The unique structure and reactivity of the aziridine ring has attracted the interest of organic chemists for many years. Of these, the cycloaddition of alkynes with aziridines via C–C bond and C–N bond cleavage is an atom-efficient and convergent approach to the preparation of valuable unsaturated N-heterocycles. In this Perspective, progress in this field is outlined on the basis of the key intermediate involved in the reaction. In addition to the cycloadditions of azomethine ylides generated by carbon–carbon bond cleavage and aziridinium ions and zwitterionic 1,3-dipoles generated by carbon–nitrogen bond cleavage, the new type of cycloadditions of aziridines and alkynes involving metalla-azetidine intermediates has been highlighted in this short review. The use of methyleneaziridine in the cycloaddition reactions with alkynes is also discussed. Contrary to noncatalytic cycloadditions of aziridines with alkynes via azomethine ylides or aziridinium ions, the catalytic cycloadditions for synthesis of unsat...