Organocatalytic asymmetric synthesis of fluorinated pyranopyrazoles

Abstract

Asymmetric fluorinated pyranopyrazoles were successfully constructed with good yields (up to 85%) and high enantioselectivity (up to 93% ee) via the reaction of unsaturated pyrazolones with α-trifluoromethyl β-fluorinated gem-diols, a method that effectively avoids detrifluoroacetylation. Furthermore, the absolute configuration of the products was unambiguously confirmed by X-ray crystallographic analysis, providing reliable structural evidence for the asymmetric transformation.