Efficient synthesis of seven-membered Aza-sultams: Heterofused amino-1,2,4-thiadiazepine dioxides

An efficient synthesis of 7-membered Aza-sultams bearing heterofused amino-1,2,4-thiadiazepine framework have been developed. Functional group pairing strategy using ambiphilic building blocks such as 1H-azole-2-carbonitrile and N-(chloromethyl)-N-methylmethanesulfonamide in the two-step base-mediated reaction sequence was described. The synthetic utility of the obtained Aza-sultams was demonstrated by hydrolysis, reduction, and cross-coupling reactions. A cascade reaction involving β-enamine sulfonamide moiety within sultam ring in the synthesis of fused pyridine heterocycle has been investigated. It should be noted that β-enamine scaffolds among ε-sultams have been first synthesized via the cyclization approach.