Tandem stereoselective synthesis of new trifluoromethylated pyranopyrazoles

• Tandem Michael addition/aromatization/cyclization reactions of pyrazolones with α,β-unsaturated trifluoromethyl ketones were developed.
• A broad range of trifluoromethylated pyranopyrazoles were synthesized in excellent yield.
• In presence of 10 mol% DABCO, the trans-products were predominantly formed in good to high diastereoselectivities.

An efficient tandem Michael addition/aromatization/cyclization reaction of pyrazolones with α,β-unsaturated trifluoromethyl ketones is described. The notable features of this tandem process are its operational simplicity, easily accessible starting materials, and mild reaction conditions. The corresponding trifluoromethylated pyranopyrazoles were obtained in excellent yields (85–99%) with good to excellent diastereoselectivities (6:1–30:1). In addition, the stereochemical assignment of the major isomer by X-ray crystallographic analysis indicated that the trans-products were predominantly formed.

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