“…[20b-d] As the most commonly used reagent for heter-oatom difluoromethylation, HCF 2 Cl (Category B) itself is an ozone-depleting substance (ODS) and its [2+1] cycloaddition only works with electron-rich alkenes. [21] Sodium chlorodifluoroacetate (Category B) has found practical applications in both gem-difluorocyclopropanation (usually at 180 8C) [22a,b] and O and N difluoromethylation (> 80 8C). [22c,d] However, the reactions suffer from disadvantages such as high temperatures or large excess of reagent.…”