4-Nitrophenyl triflate

In a related report [16] it has been further demonstrated that aryl triflates could be readily synthesised using 4-nitrophenyl triflate 33 as the transfer reagent (Scheme 8). Deprotonation of the phenol 32 with PTBD 26 in acetonitrile at an elevated temperature (80 °C), followed by the addition of 4-nitrophenyl triflate 33 gave the required aryl triflate 35 after simple filtration. Any unreacted phenolate still present was removed as the ionic polymer 34 through filtration (Scheme 8). 

Phenolic triflates are formed with 4-nitrophenyl triflate in the presence of K2CO3 in DMF or with Triflic anhydride in the presence of an amine base. It can be cleaved with Et4NOH in dioxane or with TBAF in THF (70-99% yield). Et4NOH will also cleave phenolic mesylates and tosylates. These triflates are also substrates for a variety of Pd-catalyzed coupling reactions. 

The regioselectivity of arylation of the electron-rich olefin, n-butylvinyl ether with 4-nitrophenyl triflate has been investigated129. Without added lithium salt the regioselectivity was low (fr.a = 1.5) whereas addition of a lithium halide in DMF strongly promotes / -arylation (p/oc =13) and addition of tetrabutylammonium halide in CH3CN gave a somewhat lower regioselectivity (P/[Pg.932]

Andersson, C.M. and Hallberg, A. (1988) Regioselective palladium-catalyzed arylation of vinyl ethers with 4-nitrophenyl triflate. Control by addition of halide ions. J. Org. Chem., S3, 2112-4. 

It has been shown that, in the reactions of phenoxides with 4-nitrophenyl triflate (9) in DMF, nucleophilic attack occurs at the sulfur centre (path a) however, with 2,4-dinitrophenyl triflate, attack is switched to the carbon centre (path b). Oxydehalogena-tion reactions of l-halo-2-methylsulfonylbenzenes with amino alcohol nucleophiles have been used in the synthesis of thiotomoxetine, and reactions of 2-dialkylamino-1-ethoxides with 3-aroyl-2-arylbenzothiophenes have been used in the synthesis of raloxifene. Other reports involve the methoxydehalogenation reactions of 6-halo-1,2-acenaphthylene derivatives " and nucleophilic attack on a phenylacetic mustard. ... 

Due to the importance of aryl triflates and related compounds in modern organic chemistry, including metal catalysed cross-coupling reactions, an efficient procedure for the triflation or nonaflation of phenols has been developed by the combination of PS-TBD (3 equiv.) and a perfluoroalkanesulfonyl transfer reagent (3 equiv.) such as p-nitrophenyl triflate or nonaflate [30] (Scheme 6.2). In this case, the free PS-TBD reagent could be recovered by washing successively with diluted acid, base, water and organic solvents, and almost comparable results were obtained with use of the recycled catalyst. 

Importantly, TV-carbamoyl derivatives of primary amines obtained from photolabile benzoins exist in varying proportions as cyclic hydroxyoxazolidinone tautomers. Therefore, the preparation of TV-carbamoyl derivatives of benzoins is applicable only for secondary amines and TV-alkylated amino acids. 244 At basic pH unsymmetrical benzoins, such as 3,5-dimethoxybenzoin, their mixed carbonate and carbamate derivatives, tend to equilibrate to the isomeric forms. Nevertheless, in TFA and aqueous solutions at pH 8 the structural integrity is fully maintained. 244 Preparation of 3,5-dimethoxybenzoin-derived carbamates of secondary amines and amino acids can be mediated by either CDI/methyl triflate in ni-tromethane 246 or 4-nitrophenyl chloroformate/DMAP in dry THF. 244 ... 

Aryl fluorosulfonates have recently been reported as less expensive alternatives to aryl triflates. Compound 3 has been synthesized in 50% isolated yield using 4-nitrophenyl fluorosulfonate as the electrophilic partner in the cross-coupling reaction. Roth, G. P. Fuller, C. E. J. Org. Cham. 1991,56,3493-3496. 

Arylcyclopropanes have also been prepared by metal-catalyzed carbene addition to 1,1-dimethylallene. When 4- and 3-nitrophenyldiazomethanes were decomposed with copper triflate in the presence of the allene, 2,2-dimethyl-3-methylene-l-(4-nitrophenyl)cyclopropane (7a) and 2,2-dimethyl-3-methylene-l-(3-nitrophenyl)cyclopropane (7b) were obtained in 62% and 38% yield, respectively. ... 

In 2010, Weinreb and coworkers reported their synthesis of communesin F (17) [30]. The synthesis began with known enol triflate 37. A Suzuki-Miyaura crosscoupling with 0-nitrophenyl boronic acid (38) followed by a two-step reaction with iodoaniline 39, afforded amide 40. A one-pot displacement of the benzyl group with ethyl carbamate, amide nitrogen protection, and a subsequent intramolecular Heck reaction provided enamide 41 (Scheme 5). 

IV-Phenylimidazolium triflate IV-Phenylimidazolium perchlorate 2-(Bromo)-4,5-(dicyano)imidazole IV-Methylbenzimidazolium triflate Pyridinium tetrafluoroborate IV-Methylanilinium trifluoroacetate lV-(p-Acetylphenyl)imidazolium triflate IV-Phenylimidazolium tetrafluoroborate ImidazoUum perchlorate 5-(/t-Nitrophenyl)-l//-tetrazole 4,5- (Dicy ano)imidazDle 4-(Phenyl)imidazDlium triflate Benzimidazolium tetrafluoroborate Imidazolium tetrafluoroborate Imidazolium triflate Benzimidazolium triflate 2-(Phenyl)imidazolium triflate A-Methylimidazolium triflate 4-(Methyl)imidazolium triflate l//-Tetrazole... 

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