Decarboxylative Trifluoromethylating Reagent [Cu(O2CCF3)(phen)] and Difluorocarbene Precursor [Cu(phen)2][O2CCF2Cl]. Issue 6 (12th January 2016)

• Record Type: Journal Article
• Authors: Lin , Xiaoxi; Hou , Chuanqi; Li, Haohong; Weng, Zhiqiang
• Is Part Of: Chemistry. Volume 22:Issue 6(2016)
• Page Start: 2075
• Page End: 2084
• Publication Date: 2016-01-12
• Subjects: aryl difluoromethyl ethers -- carbenes -- copper -- decarboxylation -- trifluoromethylation; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201504306
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: This article describes the new economic decarboxylative trifluoromethylating reagent [Cu(phen)(O2 CCF3 )] (1 ; phen=1, 10‐phenanthroline) and the efficient difluorocarbene precursor [Cu(phen)2 ][O2 CCF2 Cl] (2 ). Treatment of copper tert ‐butoxide with phen and subsequent addition of trifluoroacetic acid or chlorodifluoroacetic acid afforded air‐stable complexes1 and2, respectively, which were characterized by X‐ray crystallography. The copper(I) ion in1 is coordinated by a bidentate phen ligand, a monodentate trifluoroacetate group, and a molecule of CH3 CN in a distorted tetrahedral coordination geometry. The molecular structure of2 adopts an ionic form that consists of a [Cu(phen)2 ] + cation and a chlorodifluoroacetate anion. Complex1 reacted with a variety of aryl and heteroaryl halides to form trifluoromethyl (hetero)arenes in good yields. The corresponding Hammett plot exhibited a linear relationship and a reaction parameter ( ρ )=+0.56±0.02, which indicated that the trifluoromethylation reaction proceeded via a nucleophilic reactive species. Complex2 reacts with phenols to produce aryl difluoromethyl ethers in modest‐to‐excellent yields. Mechanistic investigations revealed that the difluoromethylation reaction proceeds by initial copper‐mediated formation of difluorocarbene and subsequent concerted addition of difluorocarbene to the phenol to form a three‐center transition state. Abstract : Two economic reagents, [Cu(O2 CCF3 )(phen)] for decarboxylative trifluoromethylation and difluorocarbene precursor [Cu(phen)2 ][O2 CCF2 Cl] for the difluoromethylation of phenols, are reported. These complexes react with (hetero)aryl halides and phenols to give trifluoromethyl (hetero)arenes and (hetero)aryl difluoromethyl ethers in good yields (see figure; phen=1, 10‐phenanthroline). These processes can tolerate a wide array of functional groups.