4-Methoxyphenyl triflate

Iodo-4-methoxyphenyl triflate 117 reacts with BusZnLi at room temperature to give 118 and then the butylation products 120 and 120 (equation 47)63. Intermediacy of m-benzyne 119 has been proposed for this reaction. Products derived from p-benzyne were not obtained in the reaction of p-iodophenyl triflate with the zincate. 

An interesting new addition to the methods available for constructing arylthiophenes is the addition of thienyllithium to arynes generated from aryl triflates and LDA <93JOC4722>. Both ipso-and c/ne-substitution are possible. o-Tolyl triflate gave the ortho- and we/a-substituted products in the ratio 43 57, but 2-methoxyphenyl triflate gave exclusively the weta-substituted product. 

Initially, disappointing results were obtained on attempting to crosscouple to aryl stannanes. Phenyltributyltin, tetraphenyltin, (2-methoxyphenyl)tributyltin, and (4-methoxyphenyl)tributyltin gave no coupling under Farina s conditions with vinyl triflate 80. Pleasingly,... 

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. 

Crich, D, Smith, M, 5 -(4-Methoxyphenyl) benzenethiosulfinate (MPBT)/trifluoromethanesulfonic anhydride a convenient system for the generation of glycosyl triflates from thioglycosides, Org. Lett., 2, 4067-4069, 2000. 

D. Kahne et al. developed a one-pot multicomponent stereoselective synthesis for the trisaccharide portion of cyclamycin 0 using the Kahne glycosidation.The reactivity of the glycosyl donor was tuned (the rate limiting step is the triflation of the sulfoxide) and the p-methoxyphenyl sulfoxide was activated first. The trisaccharide was obtained in an overall 25% yield with complete a-selectivity. 

The benzoylation of 2-methoxybiphenyl 26 affords the substitution product 2-(2-methoxyphenyl)benzophenone 27 in copper(II) triflate/[bmim] [BFJ, whereas traditional benzoylation with aluminum chloride, occurring exclusively at the position para to the methoxy group, is reported in the literature (Scheme 3.5). ... 

The formation of both of these side products illustrates the lability of the para-methoxyphenyl acetal-protecting group. In the case of 31, the excess dibutylboron triflate present catalyses the ring opening of the acetal and the resulting stabilized carbocation is trapped by the excess enolate. The tactic here is to establish conditions so that 31 can be eliminated. After some experimentation, we found that simply working up... 

Reductive cleavage of the /tara-methoxyphenyl (PMP-) group released the primary alcohol and the compound was converted into the corresponding methyl glycoside upon reaction with methanol in the presence of PhsP.HBr [65]. Subsequently, the primary alcohol was replaced by iodine to yield 68 to pave the way for the introduction of the exomethylene functionality required for the key Perrier s carbocy-clization reaction. Carbocycle 70 was obtained after exposure of 5-enopyranoside 69 to Hg(OCOCp3)2 in acetone/acetate buffer and the subsequent p-elimination. The synthesis of the C-ring of the alkaloid was completed by 1,4-reduction and formation of the vinyl triflate 71 with the Comins reagent. 

The lithiation-substitution of M-Boc-M-(p-methoxyphenyl)-benzylamine (4) in the presence of (-)-sparteine (5) is illustrative of an asymmetric deprotonation (Scheme 3). Lithiation of 4 with -BuLi in the presence of (-)-sparteine followed by electrophilic incorporation with methyl triflate provides (S)-6 with an enantiomeric ratio of 97 3. Generation of the epimeric organolithium intermediates by tin-lithium exchange from (S)-7 in the presence of (-)-sparteine provides the epimeric product R)-6 with a 95 5 er. Additional proof that the enantioselectivity is not established in the methylation is the demonstration that generation of the racemic organolithium species in the presence of (-)-sparteine by tin-lithium exchange of the racemic tin precursor followed by methyl triflate provides a racemic product [8]. 

Cationic polymerization can also be performed in direct miniemulsion in the presence of water. p-Methoxystyrene (p-MOS) was polymerized using the inisurf (= initiator - - surfactant) dodecylbenzenesulfonic acid with a monomer [91]. In the presence of ytterbium triflate, inverse systems were formed [92]. Although the rate of polymerization was found to be slower than for direct systems, the molecular weights obtained were shown to be larger. The polymerization was initiated by l-chloro-l-(p-methoxyphenyl)ethane (p-MOS-HCl), and catalyzed by trisdodecyl sulfate ytterbium, which served simultaneously as a surfactant and as a Lewis acid [93]. The Lewis acid surfactant did not play the expected role, however, as the p-MOS-HCl was hydrolyzed. The resulting hydronium protonated the SDS surfactant, which then served as an inisurf in the interfacial cationic polymerization process. 

The 6-endo-tng Mizoroki-Heck cyclization was also used in a few syntheses of more complex systems, especially for the formation of phenylcarbazols of type 176, which are potential anticancer agents (Scheme 5.32). In the cyclization of aryl bromide 175, a new aromatic ring is formed which might allow for high yields (175 176) [73]. In addition, 2-naphthyl triflates [74], as well as naphthyl bromides, 5-methoxyphenyl bromide and... 

Related Reagents. Benzenesulfenyl Triflate (PhSOTf) S-(4-Methoxyphenyl) Benzenethiosulfinate (MPBT). ... 

E)-1-(p-Methoxyphenyl)-3-phenyl-2-propen-1-one (5). To 4-metlx phenyl triflate... 

It has been estimated that vinyl cation, CH2=CH, lies between ethyl cation and methyl cation in its stability. The intermediacy of substituted vinyl cations in solvolysis reactions has been demonstrated, but no evidence has yet been presented for their direct observation by NMR. Even the addition of stabilizing substituents such as methoxyphenyl has failed to yield observable vinyl cations. Vinyl cations are, however, intermediates in solvolysis reactions involving very good leaving groups, specifically trifluoromethanesulfonates (triflates). The products of such reactions are allenes, acetylenes, and vinyl esters. For both trifluoroacetic acid and acetic acid solvolysis the vinyl esters are mixtures of Z and E isomers, ruling out a stereospecific substitution." ... 

Preparation by Fries rearrangement of m-methoxyphenyl cyclohexanecarboxylate in a nitromethane/toluene mixture in the presence of hafnium triflate/hthium perchlorate for 6 h at 50°. 

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