The Dimroth rearrangement. Part XV. Catalysis by methylamine salts. Preparation of 7-methylamino- and 6,7-dihydro-7-imino-v-triazolo[4,5-d]pyrimidines via 4-ethoxymethyleneamino-1,2,3-triazoles

Abstract

The rearrangement of 1,6-dihydro-6-imino-1,x-dimethyl-8-azapurines (6,7-dihydro-7-imino-y,6-dimethyl-v-triazolo[4,5-d]pyrimidines), e.g.(3) and (4), to x-methyl-6-methylamino-8-azapurines (y-methyl-7-methylamino-v-triazolo[4,5-d]pyrimidines), e.g.(5), is found to be greatly facilitated by the use of methylamine salts, in contrast to the traditional use of free amines or inorganic bases. 9-Benzyl-6-methylamino-8-azapurine has been prepared similarly. The requisite imines [e.g.(3) and (4)], members of a new and relatively basic class of 8-azapurines, were prepared by the action of free methylamine on the corresponding 5-cyano-4-ethoxymethyleneamino-x-alkyl-1,2,3-triazoles, e.g.(1) and (2).

Ionization constants and u.v., i.r., and ¹H n.m.r. spectra are recorded and discussed.