Qing-Yun Chen

Studies on fluoroalkylation and fluoroalkoxylation. Part 3. Perfluoroalkylation of olefins with perfluoroalkyl-iodides and copper in various solvenets

Abstract Perfluoroalkyl iodides react readily with simple olefins in the presence of catalytic amounts of copper in diglyme or acetic anhydride to give adducts in high yields. The reaction can be moderately accelerated by irradiation, partly suppressed with p -DNB and inhibited completely by hydroquinone. Fluorine-containing non-volatile amorphous solids were obtained when easily polymerized olefins, such as styrene and acrylates, were used as substrates. The reaction of perfluoroalkyl iodides and diallylic ether gave five-membered ring products under the same conditions. All the results seem to indicate that the reaction is a radical chain process induced by electron transfer. In DMSO, the main reaction may involve perfluoroalkylcopper intermediates which can be trapped by iodobenzene and hydroquinone and p -DNB show little inhibition effects.

Trifluoromethylation of organic halides with methyl halodifluoroacetates — a process via difluorocarbene and trifluoromethide intermediates

Abstract Treatment of methyl halodifluoroacetates, XCF2CO2Me (X = Cl, Br, I), with organic halidesRY in the presence of KF and CuI at an appropriate temperature in DMF gave thecorresponding trifluoromethylated derivatives, RCF3, in moderate to high yields. A processinvolving difluorocarbene and trifluoromethide intermediates is suggested.

A simple convenient method for preparation of difluoromethyl ethers using fluorosulfonyldifluoroacetic acid as a difluorocarbene precursor

Abstract In the presence of catalytic amounts of sodium sulfate or cuprous iodide, a variety of alkyl and aryl difluoromethyl ethers were synthesized in moderate yields by the reaction of the corresponding alcohols and phenols with fluorosulfonyldifluoroacetic acid ( 1 ) in acetonitrile under mild conditions. Fluorosulfonyldifluoroacetate anion [FO2SCF2OC2-] ( 5 ) is believed to readily eliminate SO2, CO2 and F-, thus liberating CF2:; insertion of difluorocarbene into O-H bonds and its capture by fluoride ion then result in the formation of ethers and by-product CF3H, respectively.

Studies on fluoroalkylation and fluoroalkoxylation. Part 24. Magnesium-induced single electrons transfer in reactions of fluoroalkyl iodides with alkenes and alkynes

Abstract Magnesium metal catalyses the radical reactions of perfluoroakyl iodides with alkenes and alkynes to give the corresponding adducts in high yields under mild conditions. The presence of 1,4-dinitrobenzene (p-DNB) or oxygen does not affect the reaction, but the reactions can be partially suppressed by hydroquinone and completely inhibited by 2-nitroso. 2-nitropropane in DMF. In THF fluoroalkene is obtained in addition to the normal adducts, and the reaction could be inhibited by p-DNB. All these results seem to show that a radical mechanism is involved in non-ethereal solvents. However, both radical addition and fluroalkyl Grignard reagent reactions are involved in THF. The formation of fluoroalkylmagnesium iodide is also found to proceed through a radical intermediate.

Iron-catalyzed addition reaction of fluoroalkyl iodides to alkenes

Abstract Fluoroalkyl iodides react with alkenes in the presence of catalytic amounts of iron to give the corresponding adducts in good yields, the influence of solvent on the reaction is discussed and a SET initiated radical chain mechanism is proposed.

Studies on fluoroalkylation and fluoroalkoxylation. Part 10. Electron-transfer induced reactions of perfluoroalkyl iodides and the dialkyl malonate anion and β-fragmentation of the halotetrafluoroethyl radical

Abstract Fluoroalkyl iodides, XCF2CF2I (X=F, perfluoroalkyl group) ( 1 ), react readily with malonic ester anion ( 2 ) in DMF to give ( 3 ), 1-hydroperfluoroalkane ( 4 ) and dimer of the anion ( 5 ). The reaction is accelerated by UV irradiation and partly suppressed by p-DNB. Diallyl ether (DAE) can trap the radical intermediates to afford five-membered ring products. Interestingly, in the case of 1 ( X = Cl, I ) the same reaction mainly yielded tetrafluoroethylene and 5 instead of 3 and 4 . The radical intermediate XCF2CF·2 ( X=Cl ) can also be trapped by DAE to yield tetrahydrofuran derivatives. All these results can be rationalized in terms of the SRN1 mechanism.

Studies on fluoroalkylation and fluoroalkoxylation. Part 26. Wilkinson's catalyst-induced addition of fluoroalkyl iodides to olefins

Abstract Addition of fluoroalkyl iodides to olefins in the presence of tris(triphenylphosphine)chlororhodium (I) in benzene or acetonitrile gives the corresponding 1:1 adducts in good yields. The reaction can be suppressed with p-dinitrobenzene (p-DNB) or di-t-butylnitroxide, and tetrahydrofuran derivatives are obtained from the reaction of fluoroalkyl iodides with diallyl ether. A radical chain-reaction mechanism induced by single electron transfer (SET) is proposed.

Synthesis of trifluoromethyl aryl derivatives via difluorocarbene precursors and nitro-substituted aryl chlorides

Abstract Treatment of aryl chlorides containing electron-withdrawing groups with methyl fluorosulfonyl difluoroacetate or methyl halodifluoroacetate in the presence of potassium fluoride and copper iodide gave the corresponding trifluoromethyl derivatives in moderate to high yields.

Solvent effects on the reaction of 4-chlorooctafluorobutyliodide with copper

Abstract A linear relationship between the differences of chemical shift in 19FNMR of IC F 2(CF2)3Cl and the donor number (DN) of various solvents has been found and the mechanism of the reaction of fluoroalkyl iodide with copper depends on the DN of the solvent used, which influences the product distribution in the reaction of fluoroalkyl iodide and copper with the mixture of olefin and iodobenzene in various solvents.

Studies on fluoroalkylation and fluoroalkoxylation. Part 16. Reactions of fluoroalkyl iodides with some nucleophiles by SRN1 mechanism

Abstract Fluoroalkyl iodides , XCF2CF2I (X=ClCF2CF2, Cl(CF2)4) ( 1 ), react readily with the anion of ethyl acetoacetate ( 2 ) in DMF to give ( 3 ), XCF2CF2H ( 4 ), (CH3CO)2CHCO2Et ( 5 ) and the dimer of the anion ( 6 ). The reaction can be partly suppressed with 1,4-dinitrobenzene(p-DNB) and the radical intermediate can be trapped by diallyl ether (DAE) to give the tetrahydrofuran derivatives. Anions of acetylacetone and malonitrile react also with 1 in the presence of DAE to yield the five-membered ring compounds. All these results seem to indicate that the reaction is a radical chain process induced by electron transfer. In the case of XCF2CF2I (X=Cl,I), tetrafluoroethylene and 6 , instead of 3 and 4 , are produced, showing the occurrence of β-fragmentation of the 2-halotetrafluoroethyl radical in the initiation step.