Studies on v-triazoles. Part 4. The 4-methoxybenzyl group, a versatile N-protecting group for the synthesis of N-unsubstituted v-triazoles

A series of readily prepared monocyclic N-(4-methoxybenzyl)-v-triazoles (1) have been converted into their N-unsubstituted derivatives (2) by treatment with trifluoroacetic acid at 65 °C. The procedure allows the synthesis of a range of N-unsubstituted v-triazoles. Its applicability to multicyclic systems is demonstrated by the synthesis of 3,9-dihydro-9-oxobenzopyrano2,3-d-v-triazole (5b), one of a series of compounds of interest as potential antiallergic agents.