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Copper-Catalyzed Asymmetric [4+1] Annulation of Sulfur Ylides
Catalytic Asymmetric [4 + 1] Annulation of Sulfur Ylides with Copper–Allenylidene Intermediates.
J. Am. Chem. Soc. 2016;
18 August 2016 (online)
The authors report a copper-catalyzed asymmetric [4+1] cycloaddition by trapping copper–allenylidene dipolar intermediates with sulfur ylides. A variety of chiral indolines were obtained with high stereoselectivities (≤98% ee and dr > 95:5).
This reaction affords an opportunity for the ready synthesis of chiral indoline products and related cycloadducts with high stereoselectivities. Mechanistic studies suggest that this reaction is a sequential process that involves decarboxylative propargylation/SN2 reactions promoted by binuclear copper complexes.