Recyclization of 2-imino-2H-1-benzopyrans under the influence of nucleophilic reagents. 1. New approach to the synthesis of 3-(1,3,4-oxadi-, thiadi-, and triazolyl-2)coumarins

Article abstract of DOI:10.1007/BF01165439

It has been found that under the action of hydrazides of carboxylic acids, 2-iminocoumarin-3-carboxamides are recydized to N⁽¹⁾-acylamidrazones of coumarin-3-carboxylic acids. The use of N⁽¹⁾-acylamidrazones is proposed as a simple and effective means of synthesizing 3-(1,3,4-oxadi-, thiodi-, and triazolyl-2)coumarins. The possibilities of alternate schemes of synthesis are discussed, and a mechanism is suggested for the recyclization. 1996 Plenum Publishing Corporation.