Publication Details:
Title: Ring Expansion and 1,2‐Migration Cascade of Benzisoxazoles with Ynamides: Experimental and Theoretical Studies
| Author(s) | Rajeshwer Vanjari, Shubham Dutta, B. Prabagar, Vincent Gandon, and Akhila Kumar Sahoo : Chem. Asian J. 14, 2019, 4282 |
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| Journal Name | Chemistry an Asian Journal |
| journal image URL | http://chemistry.uohyd.ac.in/~aks/wp-content/uploads/rjcaj.png |
More Details:
Demonstrated herein is a Au(I)‐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‐oximino gold carbene, and the 1,2‐migration of the sulfonamide motif to the 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‐oximino gold carbene. DFT computations also support the hypothesized mechanism and rationalize the product stereoselectivity.