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Updated: Jan 3, 2026

Preparation of Stable Bicyclic Aziridinium Ions and Their Ring-Opening for the Synthesis of Azaheterocycles
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Ring Expansion and 1,2-Migration Cascade of Benzisoxazoles with Ynamides: Experimental and Theoretical Studies
Rajeshwer Vanjari1, Shubham Dutta1, B Prabagar1
1School of Chemistry, University of Hyderabad, Hyderabad, Telangana, 500046, India.
Abstract:
Demonstrated herein is an AuI -catalyzed annulation of sulfonyl-protected ynamides with substituted 1,2-benzisoxazoles for the synthesis of E-benzo[e][1,3]oxazine derivatives. The transformation involves the addition of benzisoxazole to the gold-activated ynamide, ring expansion of the benzisoxazole fragment to provide an α-imino vinylic gold intermediate, and 1,2-migration of the sulfonamide motif to the masked carbene center to deliver the respective ring-expanded benzo[e][1,3]oxazine of predominant E configuration. A trapping experiment justifies the participation of the α-imino masked gold carbene. DFT computations also support the hypothesized mechanism and rationalize the product stereoselectivity.
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