Methanol facilitated synthesis of 7-methoxy-2-thioxo-2,3-dihydro-1H-1,3-diazepin-4(7H)-ones from nitroallylic acetates and thiourea

A novel efficient strategy for the synthesis of rare 7-methoxy-2-thioxo-2,3-dihydro-1H-1,3-diazepin-4(7H)-ones is described. Methanol, solvent for this one-step reaction, participated in this seven-membered ring closure reaction between nitroallylic acetates and thiourea. The thiourea itself also served as a base in this reaction. A possible mechanism for the reaction is proposed. (C) 2014 Elsevier Ltd. All rights reserved.