Wei-Yuan Huang

Perfluoroalkylation initiated with sodium dithionite and related reagent systems

Abstract Perfluoroalkylations promoted by sodium dithionite and related reagent systems have been reported for the following groups of compounds, viz. (i) conjugated dienes, (ii) enol ethers, and (iii) aromatic and heteroaromatic compounds. The results of some chemical conversions of the reaction products for the synthesis of useful synthetic intermediates have also been presented. A comparison between the dithionite initiated reaction and other related systems was made and discussed.

Studies on deiodo-sulfination. Part I. Studies on the deiodo-sulfination of perfluoroalkyl iodides

Abstract The normal reaction products of 5-iodo-3-oxaoctafluoropentane- sulfonyl fluoride ( I ) with K2SO3 in aqueous solution are potassium 5-iodo-3-oxaoctafluoropentanesulfinate ( II ) and 5-H-3-oxaoctafluoropentanesulfinate ( III ), but when the reaction is carried out in aqueous dioxane potassium 3-oxaoctafluoropentane-1,5-disulfinate ( IV ) is formed in high yield accompanied by a very very small amount of III . 7-Iodo-3-oxadodecafluoroheptanesulfonyl fluoride ( IX ) and 1,4-diiodo-octafluorobutane ( X ) are similarly converted into the corresponding disulfinates VII and VIII respectively. The name, deiodo-sulfination, is suggested for the conversion of RFI to RFSO2K in one step. The reaction can also be carried out in diglyme or THF but not in N-methylmorpholine, pyridine or triethylamine. The effect of light, reaction temperature, radical inhibitor, single electron scavenger, peroxide and the nature of the solvents are studied, and a radical chain mechanism involving a single electron transfer process is proposed.

Reaction of perfluoroalkyl iodides with alkenes initiated by organophosphine and related compounds

Abstract Perfluoroalkyl iodides reacted with alkenes in acetonitrile solution containing catalytic amounts of an organophosphine under mild conditions to give the corresponding adducts in moderate to high yields. Addition of hydroquinone to the reaction mixture suppressed the reaction. Diallyl ether reacted to afford tetrahydrofuran derivatives. These findings indicated that the reaction involved a free radical mechanism.

The chemistry of perfluoroalkanesulfonyl iodides

Abstract The reaction between silver perfluoroalkanesulfinate(1)(R F = a, C1(CF 2 ) 6 ; b, Cl(CF 2 ) 4 ) and iodine in dichloromethane at low temperature ( e.g. −30°C) resulted in the formation of the corresponding perfluoroalkanesulfonyl iodine(2), which was identified by its 19 F NMR spectra. The perfluoroalkanesulfonyl iodide generated in situ reacted with various olefins to form two series of adducts, namely the normal adducts, R F SO 2 CH 2 CHIR(3) and the adducts resulting from the loss of SO 2 , R F CH 2 CHIR(4) in yields ranging from moderate to good. A radical reaction mechanism is proposed and tested by e.s.r. experiments. Perfluoroalkanesulfonyl iodide reacted with acetone and other compounds containing active hydrogen to give iodinated products.

Synthesis of cholesterol and its analogs with fluorinated side-chains

Abstract Dithionite initiated addition of perfluoroalkyl iodide to an olefinic double bond proved to be an efficient method for the introduction of a perfluoroalkyl group to a steroid side chain. Starting from 3α, 6α - dihydroxy- 5β - cholanic acid, the synthesis of cholesterol and its analogs with a partially fluorinated side-chain (6a, Rf = CF2CF(CF3)2; 6b, Rf = (CF2)2CF(CF3)2; 6c, Rf = (CF2)3CF3; 6d, Rf = (CF2)4Cl; 6e, Rf = (CF2)6Cl; 6g, Rf = (CF2)6H) and bis-sterol (10) was achieved in good yield. These compounds are not degraded by some microbial organism systems.

Studies on deiodo-sulfination Part. II. The reactions of perfluoroalkanesulfinates with halogen and halogen acids and a new method for the synthesis of perfluorosulfonic acid

Abstract In the presence of a small amount of hydroquinone, reaction of potassium 3-oxaoctafluoropentane-1,5-disulfinate ( I ), 5-iodo-3-oxa- octafluoropentanesulfinate ( VII ) or 7-iodo-3-oxa-dodecafluoroheptanesulfinate ( XII ) with hydriodic acid gives the corresponding perfluorocarboxylic acid 3-oxahexafluoropentanedioic acid ( II ), 5-iodo- 3-oxahexafluoropentanoic acid ( III ) or 7-iodo-3-oxadecafluoroheptanoic acid ( XIII ), respectively. The formation of 1,5-diiodo-3-oxaoctafluoropentane ( IV ) or 1,5-dibromo-3-oxaoctafluoropentane ( VIII ) from the reaction of I or VII with I2 or Br2, respectively, has not been previously recorded in the literature. In the case of iodine this can be regarded as a retro-deiodo-sulfination. However, the reaction of the sulfinate with C12 stops at the sulfonyl chloride stage. Deiodo-sulfination provides a new method for the synthesis of perfluorocarboxylic acids, perfluoroalkyl bromide and perfluorosulfonic acid from RFI.

A Novel Nucleophilic Polyfluoroalkylating Agent RfIP(NEt2)3

Abstract In the presence of tris(diethylamino)phosphine polyfluoroalkyl iodides reacted with various aroyl chlorides to give the corresponding aryl polyfluoroalkyl ketones.

One-pot reaction for the synthesis of fluorinated β-diketones

Abstract Fluorinated β-diketones have been synthesized in high yield from the one-pot reaction of silyl enol ethers with perfluoroalkyl iodides initiates with Na 2 S 2 O 4 /NaHCO 3 , followed by treatment with diethylamine and acid hydrolysis.

Photooxidation of perhalofluorosulfinates. A simple and effective method for the synthesis of perhalofluorocarboxylic acids and their esters from the corresponding sulfonyl fluorides

Abstract Photooxidation promoted by ultraviolet irradiation of perhalofluorosulfinates afforded a simple and effective method for the synthesis of perhalofluorocarboxylic acids and their esters from the corresponding sulfonyl fluorides.

Reaction of perhalofluoroalkyl sulfinates with one-electron transfer oxidants. A facile method for the synthesis of perhalofluorocarboxylic acids

Abstract Reaction of perhalofluoroalkyl sulfinates with one-electron transfer oxidants, such as (NH 4 ) 2 S 2 O 8 , Ce(SO 4 ) 2 or H 2 O 2 /Fe 2+ afforded perhalofluorocarboxylic acids R F CO 2 H [R F  Cl(CF 2 ) 8 OCF 2 , F(CF 2 ) 8 OCF 2 , C 7 F 15 , Cl(CF 2 ) 5 ] in good yield.