(Het)aryl Difluoromethyl-Substituted beta-Alkoxyenones: Synthesis and Heterocyclizations

An efficient approach to the preparation of β-alkoxyenones bearing (het)aryl difluoromethyl substituents is described. The method included acylation of acyclic or cyclic vinyl ethers with (het)aryl difluoroacetyl chlorides. The method worked well for most substrates, except aryl-substituted derivatives bearing electron-donating groups in o- or p-positions, and heteroaromatic compounds bearing sufficiently basic nitrogen atom. Synthetic utility of (het)aryl difluoromethyl-substituted β-alkoxyenones as CCC bis-electrophiles was demonstrated by heterocyclizations with common 1,2- and 1,3-bis-nucleophiles leading to compounds with (het)aryl–CF₂–(het)aryl motif, in particular (het)aryl difluoromethyl-substituted pyrazoles, isoxazoles, and pyrimidines – promising chemotypes for drug discovery.