Preparation of Fluorine-Containing Phenylacetylenes by the Method of Introduction of the Ethynyl Group Using 1,1-Dichloro-2,2-difluroethene

Article abstract of DOI:10.1246/bcsj.61.1625

Phenylacetylenes (ArC<*>CH) having fluoro- or trifluoromethyl substituents (o-, m-, p-F; o-, m-, p-CF3; 2,4-, 2,5-, 2,6-, 3,5-(CF3)2) have been prepared from bromobenzenes (ArBr) and benzenes (ArH) using 1,1,-dichloro-2,2-difluoroethene (1) by a two-step route: ArLi or ArMgBr->ArCF=CCl2->ArC<*>CLi.Upon careful treatment at -70 deg C with 1, o-fluorophenyllithium gave o-FC6H4CF=CCl2 in good yield, together with benzyne-derived products, such as o-(o-FC6H4)C6H4CF=CCl2.Lithiation of m-bis(trifluoromethyl)benzene at 0 deg C for 9 h (24 h) followed by treatment with bromine gave 1-bromo-2,4-, 2,6-, and 3,5-bis(trifluoromethyl)benzene in 35 (38), 31 (36), and 8percent (6percent) yield, respectively.