N-Alkylation and Aminohydroxylation of 2-Azidobenzenesulfonamide gives a Pyrrolobenzothiadiazepine precursor whereas attempted N-Alkylation of 2-Azidobenzamide gives Benzotriazinones and Quinazolinones

摘要

N-Alkylation of 2-azidobenzenesulfonamide with 5-bromopent-1-ene gave an N-pentenyl sulfonamide which underwent intramolecular aminohydroxylation to give an N-(2-azidoaryl)sulfonyl prolinol, a precursor for the synthesis of a pyrrolobenzothiadiazepine. The attempted N-alkylation of 2-azidobenzamide gave a separable mixture (~1:1) of a benzotriazinone and a quinazolinone in 72% combined yield. Other primary alkyl halides (3 examples) gave similar mixtures of benzotriazinones and quinazolinones. Benzylic, allylic, secondary and tertiary alkyl halides (5 examples) gave only the benzotriazinones in moderate yields. The results of mechanistic studies show the likely involvement of nitrene intermediates in the quinazolinone pathway and a second pathway involving a DMSO or dimethylsulfide mediated conversion of 2-azidobenzamide into the benzotriazinones.