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Abstract

The preparation of new 9-arylfuro[2',3':4,5]pyrrolo[1,2-d]-1,2,4-triazolo[3,4-f]-1,2,4-triazines (V) and 7-aryl-1,4-dioxo-1,2,3,4-tetrahydrofuro[2',3':4,5]pyrrolo[1,2-d]-1,2,4-triazines (VII) from 2-aryl-4H-furo[3,2-b]pyrrole-5-carbohydrazides (I) is described. Reaction of I with triethyl orthoformate or acetate afforded 7-aryl-1,2-dihydrofuro[2',3':4,5]pyrrolo[1,2-d]-1,2,4-triazin-1-ones, or their 4-methyl analogues II giving with phosphorus pentasulfide thiones III, reacting with hydrazine to the corresponding hydrazides IV. Cyclization of IV with orthoformates, or orthoacetates led to V. Methylchloro formate reacted with I to yield N-methoxycarbonyl-2-aryl-4H-furo[3,2-b]pyrrole-5-carbohydrazides VI undergoing cyclization in an alkaline medium to VII.