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NHC-Copper(I) Halide-Catalyzed Direct Alkynylation of Trifluoromethyl Ketones on Water

An efficient and easily scalable NHC-copper(I) halide-catalyzed addition of terminal alkynes to 1,1,1-trifluoromethyl ketones, carried out on water for the first time, is reported. A series of addition reactions were performed with as little as 0.1-2.0mol% of [(NHC)CuX] (X=Cl, Br, I, OAc, OTf) complexes, providing tertiary propargylic trifluoromethyl alcohols in high yields and with excellent chemoselectivity from a broad range of aryl- and more challenging alkyl-substituted trifluoromethyl ketones (TFMKs). DFT calculations were performed to rationalize the correlation between the yield of catalytic alkynylation and the sterics of N-heterocyclic carbenes (NHCs), expressed as buried volume (%VBur), indicating that steric effects dominate the yield of the reaction. Additional DFT calculations shed some light on the differential reactivity of [(NHC)CuX] complexes in the alkynylation of TFMKs. The first enantioselective version of a direct alkynylation in the presence of C1-symmetric NHC-copper(I) complexes is also presented

The authors are grateful to Polish Ministry of Science and Higher Education for financial support of the research (grant Iuventus Plus IP2012 064172). A.P. thanks the Spanish MINECO for project CTQ2014-59832-JIN, and L.C. funding from King Abdullah University of Science and Technology (KAUS)

Wiley

Manager: Ministerio de Economía y Competitividad (Espanya)
Author: Czerwiński, Paweł
Molga, Edyta
Cavallo, Luigi
Poater Teixidor, Albert
Michalak, Michał
Abstract: An efficient and easily scalable NHC-copper(I) halide-catalyzed addition of terminal alkynes to 1,1,1-trifluoromethyl ketones, carried out on water for the first time, is reported. A series of addition reactions were performed with as little as 0.1-2.0mol% of [(NHC)CuX] (X=Cl, Br, I, OAc, OTf) complexes, providing tertiary propargylic trifluoromethyl alcohols in high yields and with excellent chemoselectivity from a broad range of aryl- and more challenging alkyl-substituted trifluoromethyl ketones (TFMKs). DFT calculations were performed to rationalize the correlation between the yield of catalytic alkynylation and the sterics of N-heterocyclic carbenes (NHCs), expressed as buried volume (%VBur), indicating that steric effects dominate the yield of the reaction. Additional DFT calculations shed some light on the differential reactivity of [(NHC)CuX] complexes in the alkynylation of TFMKs. The first enantioselective version of a direct alkynylation in the presence of C1-symmetric NHC-copper(I) complexes is also presented
The authors are grateful to Polish Ministry of Science and Higher Education for financial support of the research (grant Iuventus Plus IP2012 064172). A.P. thanks the Spanish MINECO for project CTQ2014-59832-JIN, and L.C. funding from King Abdullah University of Science and Technology (KAUS)
Document access: http://hdl.handle.net/2072/298558
Language: eng
Publisher: Wiley
Rights: Tots els drets reservats
Subject: Alquins
Alkynes
Coure
Copper
Cetones
Ketones
Density functionals
Funcional de densitat, Teoria del
Title: NHC-Copper(I) Halide-Catalyzed Direct Alkynylation of Trifluoromethyl Ketones on Water
Type: info:eu-repo/semantics/article
Repository: Recercat

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