Tunable regiodivergent phosphine-catalyzed [3 + 2] cycloaddition of alkynones and trifluoroacetyl phenylamides. Issue 12 (12th September 2017)

• Record Type: Journal Article
• Authors: Sun, Yao-Liang; Wei, Yin; Shi, Min
• Is Part Of: Organic chemistry frontiers. Volume 4:Issue 12(2017)
• Page Start: 2392
• Page End: 2402
• Publication Date: 2017-09-12
• Subjects: Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1039/c7qo00512a
• Languages: English
• ISSNs: 2052-4110

Abstract

Abstract : The regiodivergent phosphine-catalyzed [3 + 2] cycloaddition of 2-(2, 2, 2-trifluoroacetyl)phenylamides and alkynones have been achieved through adjusting the acidities of substrates, changing reaction temperature and addition of protic additive H2 O. The detailed mechanism was systematically studied. Abstract : Alkynones can be activated by phosphine as a nucleophilic catalyst, and then trapped by a series of trifluoroacetyl phenylamides to afford cycloaddition products. Through subtly adjusting the substituent of trifluoroacetyl phenylamides, the addition of water and changing the reaction temperature, two kinds of highly regioselective cycloaddition products were obtained in moderate to excellent yields. Plausible mechanisms were proposed and supported by the deuterium-labeling experiments and DFT calculations. DFT calculations demonstrate that the currently accepted intramolecular proton transfer processes involved in these reactions are impossible, and these proton transfer processes can proceed with the assistance of substrates containing an acidic moiety or by the addition of water. Our mechanistic studies provide reasonable explanations for the regioselectivity affected by the protic additive H2 O, and the reaction temperature.