Ring-size-selective construction of fluorine-containing carbocycles via intramolecular iodoarylation of 1,1-difluoro-1-alkenes

Abstract

1,1-Difluoro-1-alkenes bearing a biaryl-2-yl group effectively underwent site-selective intramolecular iodoarylation by the appropriate cationic iodine species. Iodoarylation of 2-(2-aryl-3,3-difluoroallyl)biaryls proceeded via regioselective carbon–carbon bond formation at the carbon atoms in β-position to the fluorine substituents, thereby constructing dibenzo-fused six-membered carbocycles bearing a difluoroiodomethyl group. In contrast, 2-(3,3-difluoroallyl)biaryls underwent a similar cyclization at the α-carbon atoms to afford ring-difluorinated seven-membered carbocycles.

Regio- and Enantioselective Bromocyclization of Difluoroalkenes as a Strategy to Access Tetrasubstituted Difluoromethylene-Containing Stereocenters

“…Additionally, we observed the formation of a significant amount of endo- cyclization product, 2a′ , with a yield of 25% and 49% ee. The formation of endo -cyclization product, while initially surprising, is rationalized on the basis of fluorine’s ability to stabilize α-carbocations, which can be sufficient enough to invert Markovnikov selectivity …”

Light-Mediated Dual Phosphine-/Copper-Catalyzed Atom Transfer Radical Addition Reaction

“…Indeed, two fluorine atoms exert a notable deactivating effect on the radical addition. While atom transfer reactions of perfluorinated alkenes with polyhalogenated hydrocarbons have been reported, , the use of 1,1-difluoroalkenes is rare. , At the same time, these alkenes can be readily prepared from carbonyl compounds by a Wittig-type process . When 1,1-difluoroalkenes were subjected to our standard conditions, conversions did not exceed 70%.…”

A Combined DFT, Energy Decomposition, and Data Analysis Approach to Investigate the Relationship Between Noncovalent Interactions and Selectivity in a Flexible DABCOnium/Chiral Anion Catalyst System

“…The relatively shallow slopes of the regioselectivity and exo -cyclization rates are in agreement with a concerted bromine transfer with relatively little carbocation buildup at the benzylic position. Additionally, the insensitivity of arene electronics on the endo cyclization corroborates the mechanistic hypothesis that the stabilization of α-carbocations by fluorine is the main factor leading to endo cyclization …”