Construction of 1,2‐Benzothiazine‐S,S‐Dioxide Heterocyclic Derivatives

Abstract We investigated two synthetic methods for 1,2‐benzothiazine‐S,S‐dioxide heterocyclic derivatives. The first method involves cyclization via Suzuki–Miyaura coupling, while the second achieves cyclization through intramolecular C─H activation. Specifically, when the heterocyclic ring is a pyrazole, we discovered that the reactivity of C5'─H is significantly higher than that of C3'─H. By strategically introducing a removable substituent at the C5' position, cyclization at the C3' position was achieved. These methods offer concise and efficient strategies for constructing the desired tricyclic system.