Electrolytic Partial Fluorination of Organic Compounds. 35.¹ Anodic Fluorination of 2-Pyrimidyl, 2-Pyridyl, and 2-Quinazolinonyl Sulfides

Abstract

Highly regioselective electrochemical fluorination of 2-pyrimidyl sulfides having an electronwithdrawing group (EWG) at the position R to the sulfur atom was successfully carried out using Et 4 NF‚nHF (n ) 3, 4) or Et 3 N‚3HF as a supporting electrolyte and a fluoride ion source in 1,2dimethoxyethane (DME) in an undivided cell. 2-Methylthiopyrimidine devoid of an EWG was also selectively fluorinated in DME to provide 2-(fluoromethylthio)pyrimidine in a moderate yield as 63%, while corresponding 2-methylthiopyridine was less selectively fluorinated in lower yield along with R,R-difluorinated product. In contrast, the corresponding 2-quinazolinonyl sulfides underwent similarly R-fluorination along with unexpected ipso-fluorination through anodic desulfurization.

Organocatalytic, difluorocarbene-based S-difluoromethylation of thiocarbonyl compounds

“…Dimesitylimidazolidene 4 and diphenyltriazolidene 5, which were effective in our previous O-difluoromethylation, were first examined [21]. In each case, 2a was obtained in 61% yield (Entries 1 and 2), which was confirmed using the reported spectroscopic data of 2a [27]. It must be emphasized that the Ndifluoromethylated product 3 was not observed.…”

Electrolytic partial fluorination of organic compounds

“…1 H NMR (270 MHz), 13 C NMR (68 MHz) and 19 F NMR (254 MHz) spectra were determined using CDCl 3 as a solvent.…”

“…We have systematically studied anodic monofluorination at the side chain of various heterocyclic compounds [7][8][9][10]. For example, selective anodic fluorination at the side chain of various heterocyclic compounds such as six-membered (2-pyridyl-and 4-pyrimidyl-), and five-membered (2-thiadiazolyl, 2-oxadiazolyl and 2-triazolyl) heterocycles was comparatively studied (Schemes 1 and 2) [11][12][13][14][15][16]. Thus, the active methylenethio group attached to various heterocyclic rings is selectively fluorinated to give the corresponding a-fluorinated products in moderate to good yields.…”

Electrolytic fluorination of organic compounds

“…25 Caffeine (114) was fluorinated using Et 3 N·3HF in acetonitrile to give 8-fluorocaffeine (115) in a reasonable yield (Scheme 36). 80,81 When guanosine tetraacetate (116) was oxidised under similar electrolytic conditions, 8-fluoroguanosine tetraacetate (117) was produced in a very low yield (Scheme 36). 80,81 Five-and six-membered lactams 118a,b bearing a phenylthio group were selectively fluorinated at the a position to the sulfur atom, to give the corresponding monofluorinated lactams 119a,b, as shown in (Scheme 37).…”