Synthesis of furo [3,2-e] [1,2,4] triazolo [1,5-c] -pyrimidines and furo [3,2-e] pyri-mido [4,3-f] [1,2,4] -triazin-3-one: a new ring system

ABSTRACT

2-amino-4,5-diphenylfuran-3-carbonitril [I] reacted with triethyl orthoacetate to give the 4,5-diphenyl-2-[alpha-ethoxyethylideneamino] furan-3-carbonitrile [II]. The latter compound was converted into the 5,6-diphenyl-3H, 4H-4-imino-2-methylfuro [2, 3-d] pyrimidine [III]. Reaction of [III] with alpha-cyanocinnamonitrile derivatives produced the 2-aryl-8,9-diphenyl-5-methylfuro [3,2-e] [1,2,4]-triazolo [1,5-c] pyrimidines [Va-c]. Compound III reacted with acetic anhydride to yield the 2,3-dimethyl-8,9-diphynlylfuro [3,2-e] [1,2,4] triazolo-[1,5-e] pyrimidine [VI] and with triethyl orthoformate to produce the 2-unsubstituted derivatives of VI [VII]. Reaction of III with carbon disulfide gave the 2,3-dihydro-8, 9-diphenyl-5-methylfuro-[3,2-e] [1,2,4] triazolo [1,5-c] pyrimidine-2-thione [VIII]. Compound III reacted with ethyl chloroacetate to yield the 2,3-dihydro-9, 10-diphenyl-4H-6-methylfuro [3,2-e] pyrimido [4,3-f] [1,2,4]-triazin-3-one [IX], with a new ring system