Facile one-pot three-component reaction to synthesize trifluoromethylated cyclopenta[b]pyran derivatives and their further transformation

A series of trifluoromethylated cyclopenta[b]pyran derivatives were synthesized efficiently from 1,3-cyclopentanedione, arylaldehydes, and ethyl 4,4,4-trifluoro-3-oxobutanoate via one-pot multi-component reaction catalyzed by NH4OAc. This one-pot multi-component process comprises an initial Michael addition and a subsequent intramolecular cyclization reaction. The effect of catalysts and solvents on the reaction efficiency and the yield were investigated. The structure of product 4f was further confirmed by XRD analysis. Meanwhile, further transformation of hemi-ketal moiety to the corresponding dehydrated product is also studied. In addition, a possible mechanism of this reaction is proposed herein.