Methyl tosylate

The quatemization of the nitrogen atom of the thiazole ring (the Menschutkin s reaction) by alkyl halide or methyl tosylate can be used to measure the reactivity of this atom and thus to evaluate steric and electronic effects of ring substituents. 

The quatemization of 16 2,4-dialkylthiazoles with methyl tosylate in nitrobenzene at 25 C has been studied (256) in order to examine the simultaneous influence of two substituents grouped around a reaction center (257). 

Our next concern is the solvent nucleophilicity. Schadt et al. " chose the solvolysis of methyl tosylate, which should be an Sn2 process, as the defining process. For this standard reaction the parameter / in Eq. (8-69) was set at 1.00. An empirical estimate of m, describing the sensitivity of methyl tosylate to solvent ionizing power, was obtained as the slope of the two-point line for methyl tosylate solvolysis in... 

Methoxy derivative was obtained from 2-(4,5-dihydro-l//-imidazol-2-yl)-7-hydroxy-8-methyl-2,3-dihydro-5//-pyrido[l,2,3- /e]-l,4-benzoxazin-5-one with methyl tosylate in DMF in the presence of K2CO3 at 50 °C for 1 h (99EUP894796). 

Nucleophilic displacement reactions One of the most common reactions in organic synthesis is the nucleophilic displacement reaction. The first attempt at a nucleophilic substitution reaction in a molten salt was carried out by Ford and co-workers [47, 48, 49]. FFere, the rates of reaction between halide ion (in the form of its tri-ethylammonium salt) and methyl tosylate in the molten salt triethylhexylammoni-um triethylhexylborate were studied (Scheme 5.1-20) and compared with similar reactions in dimethylformamide (DMF) and methanol. The reaction rates in the molten salt appeared to be intermediate in rate between methanol and DMF (a dipolar aprotic solvent loiown to accelerate Sn2 substitution reactions). 

Scheme 5.1-20 The reaction between halide and methyl tosylate in triethylhexylammonium...

Intriguingly, the Stille coupling of quaternary pyridylstannane 12 with 2-chloropyrazine (13) proceeded to afford adduct 14 [12]. A-Methylated 3-(tributylstannyl)pyridine 12 was easily prepared by refluxing 3-(tributylstannyl)pyridine (11) with methyl tosylate in EtOAc. By contrast, only 29% yield of the coupling adduct was isolated from the Stille reaction of 3-(tributylstannyl)pyridine A-oxide and 13. 

Figure 4. Products of acetolysis of bicyclo[2.1. l]hexane-5-methyl tosylates.

Smith and Hanson, 1971). Upon addition of NaBPh4, the free anion was converted into the ion pair, and upon addition of dibenzo-18-crown-6 [11] the ion pair was converted into the free anion. The results (Table 26) show the free anion to be much more reactive than the ion pair towards both methyl iodide and methyl tosylate. The increase in rate is again mainly due to the enhanced reactivity of the hard oxygen centre. The ratio of the rates of alkylation at the two sites of the ambident anion (kN/k0) decreased from about 1.2 for the ion pair to 0.55 and almost zero for the free anion. Increased alkylation of the hard... 

Menshutkin reaction between jV,Ar-dimethyl-d6-aniline and methyl tosylate in nitrobenzene at 51.3°C (21) is consistent with an inductive KIE resulting from the increased electron density on the nitrogen (the nucleophilicity), a steric explanation was preferred for three reasons. 

The 7V-monomethylation of primary amines RNH2 (R = CsHn, Ci2H25, Ph, PhCH2CH2 etc.) has been accomplished in high yield by condensation with 3-methyl-2-(methylthio)benzothiazolium iodide, followed by treatment of the resulting imine with methyl iodide or methyl tosylate to give the salts 49. The latter yield the products RNHMe by the action of butylamine (equation 29)76. 

With methyl tosylate as CH3X, the rates of reactions 2 and 3... 

P-Phenethylbiguanide is reported 602) to be resistant to methylation but as it behaves generally somewhat anomalously, e.g. in its stabihty towards acids (Section VII C), this provides no information as to the general behaviour of biguanides on alkylation. Thus, methyl iodide in methanol converted p-phenethylbiguanide merely into its hydriodide, and similar results were observed with methyl tosylate, and benzyl bromide. 

The living cationic ring opening polymerization (CROP) of 2-oxazolines was first reported in the 1960s [61, 62]. The polymerization can be initiated by an electrophile such as benzyl halides, acetyl halides, and tosylate or triflate derivatives. The typical polymerization mechanism for 2-alkyl-2-oxazoline initiated by methyl tosylate is shown in Scheme 6. 

Scheme 6 Schematic representation of the CROP of 2-ethyl-2-oxazoline (EtOx) initiated by the methyl tosylate...

The polymerization mixtures consisting of EtOx, SoyOx, methyl tosylate, and acetonitrile were automatically prepared utilizing the liquid handling system of... 

A library of 4 chain extended homopolymers and 12 diblock copoly(2-oxazoline)s was prepared from 2-methyl, 2-ethyl, 2-nonyl, PheOx in a very short period of time [90]. The CROP was initiated by methyl tosylate and performed in acetonitrile at 140 °C in a single-mode microwave synthesizer. A total number of 100(50 + 50) repeating units was incorporated into the respective polymer chains. The concentration of the solutions and predefined polymerization times for each monomer and comonomer are summarized in Table 11. 

First of all a 2-substituted oxazoline (1) is formed by cyclocondensation of a carboxylic acid ester with 2-aminoethanol and a small amount of (1) is converted with an alkylating agent (e.g., methyl tosylate) to the activated, ionic form (2). 

In a 100 ml three-necked flask with stirrer and thermometer 1 mol% of p-toluenesul-fonic acid methyl ester (methyl tosylate) are added to 3 g (0.03 mol) of anhydrous 2-methyl-2-oxazoline.The reaction mixture is stirred under nitrogen at 100-120 °C.The bulk polymerization sets in immediately. After 30 min. the viscous polymer melt is poured in a dish where it solidifies within minutes. After cooling to room temperature about 2 grams are dissolved in 20 ml ethanol and precipitated in 500 ml THF.The collected precipitate is dried under vacuum. 

Two general methods have been described for the synthesis of this new class of meso-ionic compounds (196). The most convenient method is by the treatment of 4-bromo-l,2,3-triazolium salts (197, X = Br) with sodium sulfide in dimethylformamide. Alternatively, N-methylation of the isomeric 4- or 5-alkylmercapto-1,2,3-triazoles 198 or 199 with methyl tosylate gave intermediate triazolium salts (197, X = SR, Y = Tos), which yielded meso-ionic l,2,3-triazole-4-thiones (196) by 5-dealkylation by heating with piperidine. 

C-marked (90% enrichment) methyl fluoride (6) has been prepared by treating 13C-marked methyl tosylate (5) with potassium fluoride at 230 °C and trapping the gaseous product at - 178 0C. 44... 

---