Copper triflate Friedel-Crafts reaction

Thio- and selenoacetals and esters are excellent substrates for mild Friedel-Crafts reactions, because of the affinity of sulfur and selenium for copper (Sch. 23). Anisole was readily acylated with methylselenoesters 94 at room temperature with activation by CuOTf to affordpnra-substituted (> 95 %) derivatives 95 [50,51]. Mercury(II) and copper(II) salts, which were effective for the activation of selenyl esters for reaction with alcohols, amines, and water, were not effective for the Friedel-Crafts reaction. Aromatic heterocycles 96 could be acylated in high yields, and the alkylation product 100 was obtained from dibutylthioacetal 99 and anisole. Vedejs has utilized this methodology in the cyclization of 101 to afford 102 in 77 % yield [52]. This intramolecular variant did not require the use of the more reactive bis copper triflate-benzene complex. 

Aliphatic nitriles react slowly with phenols and phenyl ethers in the presence of trifluoromethanesulphonic acid to give ketones after hydrolysis, in a variation of the Houben-Hoesch reaction. The crystalline complex of copper(i) triflate and benzene induces the acylation of aromatic substrates with selenol esters, affording a transition-metal mediated version of the Friedel-Crafts reaction. Aromatic carboxylic acids can be converted into symmetrical diaryl ketones in good yield by treatment of their 5-(2-pyridyl)thioesters with bis-(l,5-cyclo-octadiene)nickel [equation (15)]. In contrast to other methods for preparing symmetrical aromatic ketones, this method allows their preparation from a single starting material. 

Thioacetals eliminate to vinylsulfides in the presence of CuOTf (Scheme 46).192 Cu1 and Cu11 triflates are mild Lewis acids for Friedel-Crafts acylation and alkylation reactions. CuOTf effectively catalyzes the reaction of anisole with selenoesters.193,194 Copper(II) sulfate promotes epoxide ring opening reactions in the presence of pyridine,195 with retention of configuration being observed. Cu(OTf)2 is a catalyst for the ring opening of aziridine by aniline.196... 

Enantioselective Friedel-Crafts alkylation reactions were performed between substituted indoles and methyl trifluoropyruvate, using a chiral nonracemic ( -symmetric 2,2 -bipyridyl copper triflate complex as catalyst. The active copper(II) catalyst was... 

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