Introduction of the Difluoro(methoxy)methyl Group into the Aromatic Ring and the Study of Its Electronic Properties

A simple and efficient method for synthesizing aromatic compounds with a difluoro(methoxy)methyl fragment (CF2OCH3) by the fluorodesulfurization of thionoesters has been developed. Systematic screening identified SnCl4/DAST as the optimal reagent combination, providing excellent selectivity and high yields of target products. A series of aromatic difluoro(methoxy)methyl compounds was synthesized under these conditions. Further studies of the electronic properties of the difluoro(methoxy)methyl group using 19F NMR allowed us to determine its Hammett constants for inductive (σI) and resonance (σR) effects. The results show that CF2OCH3 acts as a moderately electron-withdrawing substituent, underscoring its potential as a versatile group for designing organic molecules with precisely tuned electronic characteristics.