Fluorinated ketene dithioacetals,: part 8.: 1,1-bis(ethylsulfanyl)perfluorobut-1-ene as starting material for the synthesis of substituted 2-trifluoromethylfurans and -pyrroles

In a two-step sequence (condensation with acetone enolate/ acid hydrolysis), 1,1-bis(ethylsulfanyl)perfluorobut-1-ene was converted into the corresponding S-ethyl 4-oxo-2-pentafluoroethylpentanethioate, This thioester proved to be a versatile intermediate, leading, in the presence of aliphatic amine, to substituted 2-trifluoromethylfurans and/or -pyrroles, The selectivity of these heterocyclisations depends on the reaction conditions and on the basicity/nucleophilicity balance of the amine. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).