Cyclization mechanisms of the cyclic dimer of aziridine aldehyde with vinyl aldehyde

Aziridine aldehydes are the notable representative of a limited number of reported amphoteric molecules containing aziridine and aldehyde groups, which can react both as an acid and as a base. In the present work, the intriguing dimerization mechanism of aziridine aldehyde free from any substituents and solvents, as well as the addition and cyclization mechanisms of its dimer with vinyl aldehyde in acetonitrile were investigated systematically. The N-H bond of aziridine aldehyde couples with the C=O bond in another aziridine aldehyde molecule, and then the O-H bond couples to the adjacent C=O bond to form a stable polycyclic dimer. In acetonitrile, aziridine aldehyde and CH2=CHCHO are inclined to cyclize to polycyclic compounds. The addition reaction of the dimer and CH2=CHCHO will form various enol and keto isomers, and the enol isomers cyclizing to 8-exo-trig aldol is energetically favorable. (C) 2017 Elsevier B.V. All rights reserved.