Regioselective synthesis of 4-alkyl- and 4-aryl-6-(perfluoroalkyl)salicylic acid derivatives by formal [3+3] cyclocondensation of 1,3-bis(silyloxy)-1,3-butadienes with 3-silyloxy-1-(perfluoroalkyl)prop-2-en-1-ones

4-Alkyl- and 4-aryl-6-(perfluoroalkyl)salicylic acid derivatives were regioselectively prepared by [3+3] cyclization of 1,3-bis(silyl enol ethers) with 3-silyloxy-1-(perfluoroalkyl)prop-2-en-1-ones.