Reactivity and regiochemical behavior in the solvolysis reactions of (2,2-difluorocyclopropyl)methyl tosylates

Recent advances in the syntheses, transformations and applications of 1,1-dihalocyclopropanes

“…The kinetics of cyclopropanation of styrene under phase transfer catalysis was investigated and the results showed that formation of a film in a liquid-liquid system and formation of a crust of a product on the surface of the solid reactant in a solid-liquid system make significant contribution to the observed kinetics. 54 53 The absolute and relative rate constants were measured and computationally confirmed.…”

“…The reactivities and the ring opening of difluorocyclopropylmethyl tosylate was studied by experimental and DFT calculation methods suggesting the involvement of cationic species in the reaction. 54…”

The preparation and properties of 1,1-difluorocyclopropane derivatives

“…The ring-opening reactions of (2,2-difluorocyclopropyl)methyl systems: Dolbier investigated the acetolysis of tosylates 104 and 105 ( Scheme 48 ) [ 96 ]. The difference between compounds 104 and 105 is the presence of a methyl substituent in 105 , which is associated with a difference in the regioselectivity of the C–C bond cleavage.…”

“…The regioselectivity of the ring opening was attributed to the stabilization of the developing cationic center by the +M effect of the fluorine atoms. The formation of the 2,2-difluorohomoallyl cation or 3,3-difluorocyclobutyl cation did not occur as a result of the strong destabilization by the −I effect of the fluorine atoms [ 96 ]. On the other hand, the principal ring-opened product of 105 derives from the cleavage of the distal bond.…”

Reactions of TFDA with Ketones. Synthesis of Difluoromethyl 2,2-Difluorocyclopropyl Ethers

“…Unlike its precursor, fluorosulfonyldifluoroacetic acid, which has also been utilized as a difluorocarbene source for conversions of acids to their difluoromethyl esters and alcohols and phenols to their difluoromethyl ethers, TFDA releases difluorocarbene in a controlled, acid-free environment that appears to be essential for high yield additions of difluorocarbene to alkenes. Indeed, TFDA been shown to be useful for adding CF 2 : to a wide variety of alkenes and alkynes, including very electron-deficient alkenes such as α,β-unsaturated esters. ,− However, in a very recent paper Chen and Xu report that TFDA is surprisingly not effective in the direct difluorocyclopropanation of α,β-unsaturated aromatic aldehydes and ketones. , Thus, they describe an indirect approach to accomplish this task, a process proceeding via the addition of difluorocarbene to the respective acetals or ketals.…”