Versatile Cyclization of Aminoanilino Lactones: Access to Benzotriazoles and Condensed Benzodiazepin‐2‐thiones
摘要:
Furanone 3 and pyranone 4 were obtained by the reaction of o-phenylene derivatives with tetronic acid 1 or pyrone 2, respectively. Under diazotization reaction, these two enaminone derivatives 3 and 4 cyclized rapidly with good yields to generate benzotriazoles 5. On the other hand, when enaminones 3 and 4 were allowed to react with carbondisulfide as electrophile, cyclization led to benzodiazepin-2-thiones 6 fused to dihydropyrone or tetronic acid moieties.
Reaction of pyrone 1a or tetronic acid 1b with o-phenylenediamine derivatives gave enaminone compounds 2. When reacting with different electrophiles, these intermediates allowed versatile access to different heterocyclic structures: when DMA derivatives or triphosgene was used, cyclization occurred through nitrogen, leading to benzimidazoles 3 and benzimidazolones 4, respectively, while reaction with