Benzyl tosylate

These rates are some four orders of magnitude slower than tosyl-ate I and even the highly reactive benzyl tosylate is slower by a factor of 200 than I. It is also noteworthy that whereas tosylate I solvolyses substantially more rapidly than III, the solvolysis of the latter is also accelerated significantly. The extremely fast rate of solvolysis for compounds I and II demand that the N-nitroso group be involved in the reaction, which we postulated to take the following course. 

When benzyl tosylate is heated in methanol, the product is benzyl methyl ether. When bromide ion is added to the reaction, the reaction proceeds at exactly the same rate, but the product is now benzyl bromide. Explain. 

Fig. 7 The Y-T plot of solvolysis of benzyl tosylates [21] in 80% aqueous acetone at 25°C r = 1.29. For interpretation of symbols, see Fig. 1. Reproduced with permission from Fujio et al. (1990b). Copyright 1990 Chemical Society of Japan.

The Menschutkin reaction of benzyl tosylates [21]-OTs with dimethyl-anilines or pyridines in acetonitrile generally proceed by a second-order bimolecular Sn2 mechanism for most ring-substituted compounds the plot of obs vs. [Nu] passes through the origin within experimental uncertainty (Yoh et al., 1989). However, for the reactions of strong ED derivatives under the same conditions, it was found that there was a significant intercept (i.e. a first-order component) in the kobs vs. [Nu] plots represented by (39) the intercept is a constant of the benzyl substrate independent of the amine nucleophiles, indicating a concurrent reaction zeroth-order in amine (Kim et al., 1995, 1998). 

Benzyl tosylates. Usual preparative methods are unsatisfactory as applied to benzyl tosylates because these esters are highly reactive and unstable. A method introduced by Kochi and Hammond consists in first forming a suspension of the... 

To avoid oversimplification, we note that changes in m values can occur independently of changes in l values when charge delocalization occurs either within the carbocation [e.g., solvolyses of benzyl substrates (3, 65, 66)] or within the anionic leaving group [e.g., solvolyses of picrates (58)]. (It has recently been shown (74) that solvolyses of benzyl tosylate do fit equation 12 satisfactorily.) Such effects appear to be general electrostatic as opposed to specific electrophilic or nucleophilic. These effects can be observed in a... 

In a similar manner 2,4-dihydroxyacetophenone with benzyl tosylate and potassium carbonate in refluxing acetone during 2-3 hours afforded the corresponding 4-benzyl ether in 69% yield (ref. 108). 

Figure 4.15 Nitrogen-carbon bond formation mediated by CD. a R = aryl, naphthyl, R, = H, CH3, R2 = aryl benzyl, tosyl, TMSCN, I h b Cbz, rt, I-4min c Cbz, rt, l-l 5 min...

Unstable benzyl tosylates may be made by deprotonation of benzyl alcohols and acylation with p-Toluenesulfonyl Chloride... 

High, but not 100%, inversion of configuration was observed in the acetolysis of chiral benzyl- 1-rf tosylate (entry 3). The decreased stereospecificity was attributed to racemization of the substrate under the reaction conditions. Substitution on benzyl tosylate may reasonably be expressed as proceeding via displacement on the substrate or intimate ion pair. 

Cerny, M. et al, Coll Czech. Chem. Comm., 1968, 33, 1143-1156 (p-D-pyr 2,4-ditosyl, -d-pyr 3-Ac 2,4-ditosyl, jl-D-pyr tri-Ac, -D-pyr benzyl tosyl, fl-D-pyr benzyl, j3-D-pyr acetyl benzyl tosyl)... 

We have also found that our Mg reacts with tosylates to give good yields of the coupled products. For example, benzyl tosylate reacts in refluxing THF to give the expected bibenzyl in 84% yield after 12 h. Neat hexane-1,6-ditosylate reacted with Mg after 36 h at 90-100°C to give a polymer with an average carbon chain length of 26.5. Mass spectrometry (El) revealed masses up to 1135 amu, but much of the sample was unable to be volatilized. Butyl tosylate did not react easily with the Mg. ... 

We reported that Mn does, in fact, undergo oxidative addition to alkyl and benzylic tosylates and mesylates under mild conditions to yield the corresponding organomanganese tosylates and mesylates in excellent yields. To our knowledge, this is the first example of organomanganese tosylates and mesylates prepared via direct oxidative addition of manganese metal or by any metathesis approach. 

SnI examples. A. Heterolysis of a tertiary carbon-bromine bond. B. Heterolysis of a benzyl-tosylate bond. 

The solubility of ionic substances in relatively nonpolar aprotic solvents can be greatly enhanced by using catalytic quantities of macrocyclic polyethers, such as 18-crown-6, the structure of which is shown in Fig. 5.5. These macrocyclic ethers selectively solvate the cation, both enhancing solubility and also leaving the anion in a very weakly solvated state. The anions behave under these conditions as highly reactive species, sometimes termed naked anions. A study of the relative rates of nucleophilic substitution on benzyl tosylate by potassium salts in acetonitrile in the presence of 18-crown-6 revealed a pronounced leveling effect. " All the potassium halides (fluoride, chloride, bromide, and iodide) were approximately equal in their reactivity. Potassium acetate was observed to be almost ten times more reactive than potassium iodide under these conditions—a reversal of the normal reactivity of acetate ion versus iodide ion in nucleophilic substitution reactions. As measured by cHji values in Table 5.5, iodide is 3 log units, i.e., 10 times, more reactive than acetate ion in the protic solvent methanol. 

Methoxyphenyl)methyl 4-methylbeiizenesu]fonate (A primary benzylic tosylate)... 

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