2,4,6-Trimethylpyridinium triflate

Preparation of 2-Fluoro-4-methylacetamlide, 166 Fluorination with A-ferf-Butyl-Al-fluorobenzenesulfonamide Preparation of 1-Fluoro-l-octene, 166 Fluorination with A-Fluoro-2,4,6-trimethylpyridinium Triflate Preparation of Diethyl Fluorophenylmalonate, 166 Fluorination with Xenon Difluoride... 

At rt l-fluoro-2,4,6-trimethylpyridinium triflate (Id 0.14g, 1 mmol) was added in several portions to a THF solution of the sodium salt of diethyl phenylmalonate [prepared in situ by treating diethyl phenyl-malonate (0.236 g, 1 mmol) with 60% NaH in oil (0.024 g, 1 mmol) in THF (2 mL) at 0°C]. After 30 min the reaction mixture was poured into dil HC1 and extracted with Et20. The extract was washed with aq NaHCO, and then with H20, dried (anhyd MgS04), filtered, and evaporated. The resulting residue was column chromatographed (silica gel, CH2Cl2/hexane 1 1) to give an oil yield 83%. 

Treatment of the sodium salts of 5-methyl(or-ethyl,-benzyl)-l,3-oxazine-4,6-dione 19 with l-fluoro-2,4,6-trimethylpyridinium triflate (Id) in tetrahydrofuran/hexamethylphosphoric triamide at — 78 °C gives the 5-fluoro derivatives 20 in high yield.58... 

A general method for the preparation of monofluorinated chiral building blocks has been developed which consists of fluorination of methyl 8-phenylmenthyl monoalkylmalonates 24 using lithium hexamethyldisilazanide and l-fluoro-2,4,6-trimethylpyridinium triflate (Id).63... 

To a stirred solution of methyl 8-phenylmenthyl methylmalonate (250 mg, 0.72 mmol) in dry THF (5 mL) was added at — 78 C under argon 1 M LiHMDS in THF (1.1 mL, 1.1 mmol). The mixture was stirred for 30 min at — 78 C, after which l-fluoro-2,4,6-trimethylpyridinium triflate (Id 310mg. 1.1 mmol) was added in small portions. The resulting mixture was stirred for 15 h at — 78 C to rt, before dilution with benzene. The mixture was washed with 5 % aq KHS04 and brine, dried (MgS04). and evaporated. Column chromatography of the residue (silica gel, hexane/EtOAc 95 5) gave an epimeric mixture of the fluorides as an oil yield 225 mg (87%). 

C9H10O3 methyl 2-hydroxy-4-methylbenzoate 4670-56-8 15.00 1.1483 1 16884 C9H11F4N03S N-fluoro-2,4,6-trimethylpyridinium triflate 107264-00-6 25.00 1.3855 2... 

Abbreviations Ac acetyl Bn benzyl BSP 1-benzenesulfinyl piperidine BTIB bis(trifluoroacetoxy)iodobenzene DAST (diethylamino)sulfur trifluoride DDQ 2,3-dichloro-5,6-dicyano-/)-benzoquinone DMDO dimethyldioxirane DMTSF dimethyl(methylthio)sulfonium tetrafluoroborate DMTST dimethyl(methylthio)sulfonium triflate DTBMP 2,6-Ai-tert-butyl-4-methylpyridine DTBP 2,6-di-tert-butylpyridine DTBPl 2,6-di-tert-butylpyridinium iodide FDCPT l-fluoro-2,6-dichloropyridinium triflate FTMPT l-fluoro-2,4,6-trimethylpyridinium triflate IDCP iodonium dicollidine perchlorate IDCT idonium dicollidine triflate LPTS 2,6-lutidinium p-toluenesulfonate LTMP lithium tetramethylpiperidide Me methyl MPBT S-(4-methoxyphenyl) benzenethiosulflnate NBS A-bromosuccinimide NIS A-iodosuccinimide NlSac A-iodosaccharin PPTS pyridinium p-toluenesulfonate TBPA tris(4-bromophenyl)ammoniumyl hexachloroantimonate Tf trifluoromethanesulfonyl TMTSB methyl-bis(methylthio)sulfonium hexachloroantimonate TMU tetramethylurea Tr trityl TTBP 2,4,6-tri-tert-butylpyrimidine. 

The reaction of 2-arylbenzoxazoles with Al-chlorosuccinimide in the presence of a palladium catalyst yields the chlorinated product (4). However, in the related ace-toxylation process, the reaction occurs at the position ortho to nitrogen in the aryl ring and involves a palladated intermediate. The palladium-catalysed reaction of Al-arylamides with Al-fluoro-2,4,6-trimethylpyridinium triflate, a source of F, results in selective ortho-fluorination and may lead to mono- or di-fluorinated benzoic acids. Here, (5) is a likely intermediate. A review of selectivity in electtophilic Auorinations has been published. ... 

Although NFSI was successful for the monofluorinations, it was not as active in the difluorination reactions and tended to form mixtures of the mono- and difluorinated compounds. After some experimentation, N-fluoro-2,4,6-trimethylpyridinium triflate was found to be more active in the difluorination reaction and generated moderate to excellent yields of the functionalized compounds (Example 7.18). 

A mixture of oxalamide (0.2 mmol, 1.0 equiv), Pd(OAc)j (44mg, 0.10 equiv), A-fluoro-2,4,6-trimethylpyridinium triflate (0.6nunol, 3.0 equiv), and 1,4-dioxane (2mL) in a 25mL glass vial (sealed with PTFE cap) was heated at 80 °C for 24h. The reaction mixture was cooled to room temperature and concentrated in vacuo. The resulting residue was purified by column chromatography on silica gel to give the product as a pale yellow oil (80%). 

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