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Gold-Catalyzed [5+2]- and [5+1]-Annulations between Ynamides and 1,2-Benzisoxazoles with Ligand-Controlled Chemoselectivity

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posted on 2018-09-20, 00:00 authored by Prakash D. Jadhav, Xin Lu, Rai-Shung Liu
This work describes two distinct annulations between ynamides and 1,2-benzisoxazoles with chemoselectivity controlled by ligands. With IPrAuCl/AgNTf2, aryl-substituted ynamides undergo [5+2]-annulation reactions, whereas P­(t-Bu)2(o-biphenyl)­AuCl/AgNTf2 alters the chemoselectivity of the same ynamides to implement [5+1]-annulation reactions. 13C-Labeling experiments confirm that a 1,2-sulfonamide shift is involved in the [5+1]-annulation process. A plausible mechanism is postulated to rationalize the mechanisms of the two annulations.

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