Selective reactions of 1,1-cycloalkanedicarboxylic acids with SF4. A route to 1,1-bis(trifluoromethyl)cycloalkanes, 1-fluoroformyl-1-(trifluoromethyl)cycloalkanes and 1-(trifluoromethyl)-1-cycloalkanecarboxylic acids

Six-, five-, four- and three-membered 1,1-cycloalkanedicarboxylic acid (2a–d) were synthesized by alkaline hydrolysis of the corresponding diesters (1a–d) and the reactions of the formers with SF4 were investigated. 1,1-Bis(trifluoromethyl)cycloalkanes (3a–d) were the products of the reactions conducted at 120–150°C while at 30°C 1-fluoroformyl-1-(trifluoromethyl)cycloalkanes (4a–d) were exclusively formed. The latter were isolated as pure compounds or converted in situ into 1-(trifluoromethyl)-1-cycloalkanecarboxylic acids (5a–d).