Chlorodifluoromethyl aryl ketones and sulfones as difluorocarbene reagents: The substituent effect

We have investigated the different chlorodifluoromethyl aryl ketones 1a–1g and sulfones 2a–2h as difluorocarbene reagents for O- and N-difluoromethylations. It was found that the sulfone reagents 2 were generally more efficient in difluoromethylation than the ketone reagents 1. Furthermore, while the different substituents on ketone reagents 1 did not show a remarkable impact on the difluoromethylation reaction, the substituent effect on the sulfone reagents 2 was much more significant. Finally, we found that p-chlorophenyl chlorodifluoromethyl sulfone 2d and p-nitrophenyl chlorodifluoromethyl sulfone 2h were among the most powerful difluorocarbene reagents in this category for O-difluoromethylations.

This paper describes the interesting substitution effect in chlorodifluoromethyl aryl ketones and sulfones as difluoromethylating agents for phenols. It was found that, while the different substitution groups on ketone reagents 1 did not show a remarkable impact on the difluoromethylation reaction, the substitution effect on the sulfone reagents 2 was much more significant. Finally, we figured out that p-chlorophenyl chlorodifluoromethyl sulfone 2d and p-nitrophenyl chlorodifluoromethyl sulfone 2h were among the most powerful difluorocarbene reagents in this category.Figure optionsDownload as PowerPoint slideHighlights
► Chlorodifluoromethyl aryl ketones 1 and sulfones 2 were surveyed as:CF2 reagents.
► The substitution groups on reagents 1 and 2 showed different effect on their reactivity.
► Two of the most efficient difluorocarbene reagents in this category have been selected.
► The different substitution effects on 1 and 2 were rationalized.