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Updated: Jul 16, 2026

Efficient Synthesis of Polyfunctionalized Benzenes in Water via Persulfate-promoted Benzannulation of α,β-Unsaturated Compounds and Alkynes
Published on: December 16, 2019
Synthesis of 8-Membered Benzosultam-Bridged 1,4-Benzoxazines via Cascade Oxetane Ring-Opening Cyclization/SNAr
Hemanga Bhuyan1, Abhijit Gogoi1, Shatabdi Barman1
1Department of Chemical Sciences, Tezpur University, Napaam, Sonitpur, Tezpur, Assam 784028, India.
Abstract:
A transition-metal-free, tandem one-pot double cyclization of N-(2-(3-oxetanyloxy)aryl)-2-fluoroarenesulfonamides has been developed, providing an unprecedented entry into 8-membered benzosultam-bridged 1,4-benzoxazines. The reaction proceeds via an initial intramolecular 6-exo-tet oxetane ring-opening cyclization, followed by a rapid, concomitant SNAr cycloetherification to deliver the desired products in high yields (up to 92%). When applied to N-(2-(3-oxetanyloxy)aryl)-4-nitroarenesulfonamides, the reaction shifts to a second, unprecedented two-step cascade sequence combining the oxetane ring-opening cyclization step with a desulfonylative Smiles rearrangement to afford 2-substituted 1,4-benzoxazines. Notably, under more forcing conditions, this reaction can be extended into a three-step cascade process involving a classical Smiles rearrangement as the terminating step.
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