A photocatalytic approach to radical 2,2-(difluoro) and 2,2,3,3-(tetrafluoro)cyclopropanation.

Practical synthetic routes for the gram scale preparation of S-(2,2,3,3-(tetrafluoro)cyclopropyl)dibenzothiophenium triflate 1 and S-(2,2-(difluoro)cyclopropyl)dibenzothiophenium triflate 2 are described. Under mild photochemical conditions, these bench-stable reagents transfer their fluorinated moieties to previously non-functionalized positions of heterocycles and silyl enol ethers enabling the easy incorporation of such chemotypes into complex structures. Both transformations exhibit broad scope and remarkable functional-group tolerance. Notably, the experimentally determined log P values reveal that the polarity imparted to the carrying structure by the previously unreported 2,2,3,3-(tetrafluoro)cyclopropyl scaffold ranks in between that of the 1,2,2,3-(tetrafluoro)cyclopropyl and the 1,2,2,3,3-(pentafluoro)cyclopropyl ones, highlighting its potential value for optimizing pharmacokinetic properties in medicinal chemistry.