A Convenient Preparation of Fluorinating Reagent F‐TEDA Bearing Bisphenylsulfonylimide Counterion and Its Fluorination to Oxindoles

The direct preparation of a kind of fluorinating reagent 1 [F‐TEDA‐N(SO₂Ph)₂] was realized in high yield via the complexation of N‐fluorobenzenesulfonimide (NFSI) with 1‐(chloromethyl)‐1,4‐diazabicyclo[2.2.2]octan‐1‐ium N′,N′‐bis‐(benzenesulfonylimide) salt. In its fluorination to oxindoles, the fluorinating products 6 were afforded in moderate to high yields.     

Bench-Stable Electrophilic Fluorinating Reagents for Highly Selective Mono- and Difluorination of Silyl Enol Ethers

Efficient methods for the synthesis of fluorinated compounds have been intensively studied, recently. Development of practical fluorinating reagents is indispensable for this purpose. Herein, bench-stable electrophilic fluorinating reagents were synthesized as N-fluorobenzenesulfonimide (NFSI) substitutes. Reagents obtained by replacing one of the NFSI sulfonyl groups with an acyl group led to the highly selective monofluorination of silyl enol ethers with suppression of undesired overreaction, that is, difluorination. On the other hand, reagents bearing electron-withdrawing substituents at NFSI benzenesulfonyl groups efficiently facilitated the difluorination of silyl enol ethers under base-free conditions. Thus, both mono- and difluorinated target materials were prepared from the same substrate.     

Pd(PPh3)4-catalyzed direct ortho-fluorination of 2-arylbenzothiazoles with an electrophilic fluoride N-fluorobenzenesulfonimide (NFSI)

An efficient protocol was developed for regio-selective Pd-catalyzed direct ortho-fluorination of 2-arylbenzo[d]thiazoles using N-fluorobenzenesulfonimide (NFSI) as the F⁺ source, and l-proline as the crucial promoter. The present method offered a practical route to synthesize valuable fluorinated products, which are of potential importance in the pharmaceutical and agrochemical industries.     

DABCO-mediated one-pot sequential transformation: convenient access to fluorinated 1H-pyrazol-5(4H)-ones

A Lewis base-mediated one-pot sequential transformation of pyrazolones with Morita-Baylis-Hillman (MBH) carbonates and N-fluoro-N-(phenylsulfonyl)benzenesulfonamide (NFSI) has been developed. By using this process, a series of fluorinated pyrazolone derivatives have been synthesized in 40-83% yields.     

Retracted: A Facile Synthetic Route to New Fluorinated Building‐Blocks of 1‐Fluoroalkynes and 1‐Fluorodiynes

A facile and direct fluorination process of alkynes and diynes was developed. In the presence of n‐butyllithium, the reaction of a series of terminal alkynes and diynes with the electrophilic fluorinating reagent (NFSI) proceeded to afford various 1‐fluoroalkynes and 1‐fluoro‐1,3‐diynes in moderate to high yields.     

A convenient method for the synthesis of fluorinated α-cyanoacetates via phase-transfer catalysis

A simple and convenient method for the synthesis of fluorinated α-cyanoacetate derivatives has been developed by using electrophilic fluorination of allyl and benzyl substituted α-cyanoacetates with N-fluorobenzensulfonimide (NFSI) as electrophilic fluorinating agent via phase transfer catalysis. The reaction is transition metal free and carried out in aqueous and mild reaction conditions in the presence of readily available tetra-N-butylammonium iodide (TBAI) as phase-transfer catalyst.     

Ligand‐Promoted Iron(III)‐Catalyzed Hydrofluorination of Alkenes

An iron‐catalyzed hydrofluorination of unactivated alkenes has been developed. The use of a multidentate ligand and the fluorination reagent N‐fluorobenzenesulfonimide (NFSI) proved to be critical for this reaction, which afforded various fluorinated compounds in up to 94 % yield.     

Catalytic enantioselective fluorination and amination of beta-keto phosphonates catalyzed by chiral palladium complexes

[reaction: see text] The catalytic enantioselective fluorination and amination of beta-keto phosphonates catalyzed by chiral palladium complexes is described. Treatment of beta-keto phosphonates with N-fluorobenzenesulfonimide (NFSI) as electrophilic fluorinating reagent and diethyl azodicarboxylate (DEAD) as electrophilic amination reagent under mild reaction conditions afforded the corresponding alpha-substituted beta-keto phosphonates in moderate to excellent yields with excellent enantiomeric excesses.     

Ionic liquids as recyclable solvents for diethylaminosulfur trifluoride (DAST) mediated fluorination of alcohols and carbonyl compounds

The first simple and efficient method for the synthesis of mono and gem-difluorinated molecules using [C₈mim][PF₆] ionic liquid as a recyclable solvent medium with diethylaminosulfur trifluoride (DAST) as the fluorinating reagent, is reported.     

Development of a scalable synthesis of a nonbasic inhibitor of the serine protease tryptase

A chromatography-free process for the synthesis of a bis(benzimidazole)difluoromethane inhibitor of the serine protease tryptase is described. This synthesis features the introduction of the gem-difluoro moiety using the electrophilic fluorinating reagent N-fluoro-bis(phenylsulfonimide) as well as the stepwise introduction of both benzimidazole rings. A protocol for the destruction of reactive, process-related substances produced in the synthesis is also presented.     

Fluorination with ionic liquid EMIMF(HF)2.3 as mild HF source

Hydrogen fluoride is a basic fluorinating reagent, but handling it is difficult. For this reason, some modified fluorinating reagents such as HF-pyridine, Et₃N-HF, and poly(hydrogen fluoride) complex have been developed. Those reagents, however, still require aqueous work-up procedures which generate hydrogen fluoride. Recently, ionic liquids have received much attention because of the ease in handling them and the possibility of non-aqueous work-up. An ionic liquid, 3-ethyl-1-methyimidazolium oligo hydrogen fluoride (EMIMF(HF)_2.3), which is stable in air and moisture, can be used as a hydrogen fluoride equivalent for some fluorination reactions; it does not require an aqueous work-up.     

Synthesis of N-phosphoryl amino acids using bis(9-fluorenylmethyl)phosphite

Bis(9-fluorenylmethyl)phosphite (BFMP) was found to be an effective reagent for the N-phosphorylation of various amino acid methyl esters. BFMP was prepared from N,N-diisopropyl phosphoramidous dichloride in a one-pot two-step reaction and was obtained as a crystalline solid. N-Phosphorylation of the methyl esters of seven representative amino acids with BFMP was high-yielding and generally resulted in crystalline products. Complete deprotection of both the 9-fluorenylmethylphosphosphate esters and the amino acid methyl esters was accomplished concomitantly with LiOH to give N-phosphoryl amino acids.     

Reactions of methylenecyclopropanes and vinylidenecyclopropanes with N-fluorodibenzenesulfonimide

Methylenecyclopropanes and vinylidenecyclopropanes undergo ring-opening reactions with N-fluorodibenzenesulfonimide (NFSI) upon heating at 60 °C in tetrahydrofuran to give the corresponding fluorinated derivatives 2 and 6 in good to excellent yields. A plausible reaction mechanism has been discussed on the basis of previous literature.     

N,N-Dichlorobis(2,4,6-trichlorophenyl)urea (CC-2) as a new reagent for the synthesis of pyrimidone and pyrimidine derivatives via Biginelli reaction

A simple and efficient method for the synthesis of 3,4-dihydropyrimidin-2-(1H)one and benzo[4,5]imidazo/thioazo[1,2-a]pyrimidine derivatives has been described using N,N′-dichlorobis(2,4,6-trichlorophenyl)urea (CC-2) as a new reagent. This method is found to be efficient and convenient for the synthesis of pyrimidone and pyrimidine derivatives.     

Copper-catalyzed intermolecular aminochlorination of alkenes

A copper-catalyzed radical and regioselective aminochlorination of alkenes using N-fluoro-benzenesulfonimide (NFSI) and TMSCl as nitrogen and chlorine sources respectively is reported.     

The investigation of fluorination reaction of p-substituted benzenesulfonimides with fluorine–nitrogen mixed gas to synthesize NFSI analogues

This paper studied the fluorination reaction of p-substituted benzenesulfonimides with diluted elemental fluorine to synthesize N-fluoro-benzenesulfonimide (NFSI) analogues. Several synthetic methods were compared and we found that, for many p-substituted benzenesulfonimides, the fluorination of their sodium salts with 10% F₂–N₂ mixed gas in acetonitrile at room temperature could afford NFSI analogues in moderate to good yields.     

Asymmetric synthesis of (−)-(S,S)-homaline

The asymmetric synthesis of (−)-(S,S)-homaline was achieved in 8 steps from commercially available starting materials using the diastereoselective conjugate addition of the novel lithium amide reagent lithium (R)-N-(3-chloropropyl)-N-(α-methyl-p-methoxybenzyl)amide to methyl cinnamate to install the correct stereochemistry. Subsequent functional group manipulation of the resultant β-amino ester and Sb(OEt)₃-mediated macrolactamisation was followed by homodimerisation to give (−)-(S,S)-homaline in 18% overall yield, representing the first asymmetric, and by far the most efficient synthesis of this natural product reported to date.     

Novel synthesis of α-nitroalkenes from nitroalkanes via halogenation of intermediate N,N-bis(silyloxy)enamines

An approach to conjugated nitroalkenes via oxidation of N,N-bis(silyloxy)enamines with bromine or iodine in the presence of tetra-n-butylammonium acetate is described. The acetate ion plays a key role by acting as a mild desilylating reagent. This new strategy allows the synthesis of α-nitroalkenes from the corresponding nitroalkanes.     

The synthesis and 1H NMR study of vinyl organometallic monomers: (η5-C5H4CHCH2)M(CO)2(NO) (M = Cr,Mo, W) and (η5-C5H4CHCH2)M(CO)2 (M = Co,Rh, Ir)

A reaction between 6-methylfulvene and lithium diisopropylamide in THF solution produces vinylcyclopentadienyllithium in yields of 85–95%. The ¹H NMR spectrum of this air-sensitive organlithium reagent has been recorded in THF-d₈. Reactions of vinylcyclopentadienyllithium with Group VIB metal hexacarbonyls followed by treatment with N-methyl-N-nitroso-p-toluenesulfonamide afford the new vinyl organometallic monomers (η⁵-C₅H₄CHCH₂)M(CO)₂(NO) (M = Mo, W). Vinylcyclopentadienyllithium also serves as a convenient precursor to a series of (η⁵-vinylcyclopentadienyl)dicarbonylmetal monomers of cobalt, rhodium, and iridium. The ¹H NMR spectra of these vinylcyclopentadienylmetal derivatives have been compared as a function of the metal.     

Dianion of N-phenyl-2-(phenylsulfonylmethyl)propenamide: an efficient synthetic reagent for (E)-trisubstituted olefins and 5,6-dihydro-2H-pyrans

The dianion of N-phenyl-2-(phenylsulfonylmethyl)propenamide was found to be an efficient reagent for the synthesis of (E)-α,β-unsaturated amides and 5,6-dihydro-2H-pyrans.