Hideki Ishii

Electroorganic synthesis under solvent-free conditions. Highly regioselective anodic monofluorination of cyclic ethers, lactones, and a cyclic carbonate

Abstract Regioselective anodic fluorination of cyclic ethers, lactones, and a cyclic carbonate in Et 4 NF· n HF ( n =4, 5) and Et 3 N·5HF without a solvent was successfully carried out to give the corresponding monofluorinated products in moderate yields. This is the first report of direct electrochemical fluorination of cyclic ethers, lactones, and a cyclic carbonate using anodic fluorination.

Electrolytic partial fluorination of organic compounds ☆: Part 44. Anodic gem-difluorodesulfurization using triarylamine mediators

Indirect anodic gem-difluorodesulfurization of dithioacetals was successfully carried out using triarylamine mediators to provide gem-difluoromethylene compounds in moderate to good yields.

Selective anodic fluorination of phthalides in ionic liquids

Anodic fluorination of phthalide and its derivatives was carried out using Et4NF·4HF, Et3N·5HF and imidazolium ionic liquids like 1-ethyl-3-methylimidazolium triflate [emim][OTf]. Despite the high oxidation potential of phthalide, the fluorination proceeded efficiently in ionic liquids (ILs) containing fluoride salts. Fluorodesulfurization of 3-phenylthiophthalide took place predominantly in [emim][OTf] and CH2Cl2 while the use of 1,2-dimethoxyethane (DME) resulted in selective α-fluorination without the desulfurization. It was also demonstrated that the electrochemical fluorodesulfurization could be achieved by the reuse of IL. This is the first example of selective anodic fluorination using imidazolium ionic liquids.

Regioselective Anodic Monofluorination of Ethers, Lactones, Carbonates, and Esters Using Ionic Liquid Fluoride Salts

Regioselective anodic fluorination of various cyclic and open-chain oxygen compounds like ethers, lactones, carbonates, and esters in ionic liquids, Et 4 NF-nHF and Et 3 N-nHF (n = 4,5) without a solvent was successfully carried out to give the corresponding monofluorinated products in moderate to high yields. It was demonstrated that some fluorinated ethers were isolated simply by distillation of the electrolytic solutions. This is the first example of successful partial anodic fluorination under completely solvent-free conditions.

Electrolytic partial fluorination of organic compound. Part: 53 Highly regioselective anodic mono- and difluorination of 4-arylthio-1,3-dioxolan-2-ones. A marked solvent effect on fluorinated product selectivity☆

Anodic fluorination of 4-arylthio-1,3-dioxolan-2-ones was investigated using various supporting fluoride salts and solvents. Their fluoro-desulfurization took place predominantly in Et4NF·5HF/CH2Cl2 while the use of Et4NF·4HF/DME resulted in α-fluorination, without the desulfurization, selectively. Electrolytic solvents affected markedly the product selectivity as compared with supporting fluoride salts. This is the first example of a solvent effect on the fluorinated product selectivity in the anodic fluorination.

Electrolytic Partial Fluorination of Organic Compounds. Part 41: Highly Selective Electrolytic Fluorination of Dimethoxyethane, its Homologues, and Crown Ethers

Abstract The anodic fluorination of dimethyoxyethane (DME), and diethylene glycol dimethyl ether in acetonitrile containing a fluoride salt as a supporting electrolyte and a fluoride ion source using an undivided cell provided the corresponding monofluoromethyl ethers as a main product in good yields. On the other hand, anodic fluorination of crown ethers resulted in carbon–carbon bond cleavage which led to the selective production of α,ω-difluoro products with high yields. A carbon anode as well as a platinum anode was found to be effective for the electrolytic fluorination when Et 3 N·5HF was used as the supporting electrolyte.

Anodic benzylic fluorination of toluene, ethylbenzene, and cumene derivatives

Abstract Anodic fluorination of toluene, ethylbenzene, and cumene derivatives was comparatively studied using Et 4 NF-4HF as a supporting electrolyte and a fluorine source. Anodic benzylic fluorination occurred except for some cumene derivatives and the yields of the fluorinated products greatly depended on the stability of benzylic cations.

Electrolytic partial fluorination of organic compounds. Part 48: Anodic fluorination of 2-cyano-1-methylpyrrole

Abstract Anodic fluorination of 2-cyano-1-methylpyrrole using Et 3 N·2HF in an undivided cell provided the corresponding 5-fluoropyrrole and 2,5,5-trifluoro-1-methyl-3-pyrrolin-2-carbonitrile while the use of Et 3 N·3HF afforded selectively the latter product, which was readily hydrolyzed to isolable 5,5-difluoro-1-methyl-3-pyrroline-2-one. This is the first report of successful anodic fluorination of a pyrrole derivative.

Electrolytic partial fluorination of organic compounds. Part 50: Highly selective anodic mono- and difluorination of 4-phenylthiomethyl-1,3-dioxolan-2-one and its synthetic application

Abstract Anodic fluorination of 4-phenylthiomethyl-1,3-dioxolan-2-ones was successfully carried out to provide the corresponding α-mono- and α,α-difluorinated products selectively, depending on the amount of the electricity passed. The fluorination was also greatly affected by solvents, temperature and current densities. The fluorinated products were readily converted into the corresponding fluorinated allyl alcohol and diols by treatment with an alkaline solution.

Electrolytic partial fluorination of organic compounds. Part 65: Regioselective anodic difluorination of oxazolyl sulfides

Abstract Electrochemical fluorination of 2-alkylthio-4-methyloxazoles has been successfully carried out using Et4NF·nHF (n=4, 5) as the supporting electrolyte and fluoride source to provide the corresponding 2-alkylthio-4,5-difluoro-4-methyl-2-oxazolines, and fluorination did not take place at α to the sulfur atom. In the case of electrochemical fluorination of 2-methylthio-4-cabomethoxyoxazole afforded a 2,5-difluoro-3-oxazoline derivative in addition to a 4,5-difluoro-2-oxazoline one. In contrast, anodic fluorination of 2,4,5-trimethyloxazole devoid of a thio group resulted in no formation of fluorinated products.