P-toluenesulfonic chloride

When It IS necessary to prepare secondary alkyl halides with assurance that no trace of rearrangement accompanies their formation the corresponding alcohol is first converted to its p toluenesulfonate ester and this ester is then allowed to react with sodium chloride bromide or iodide as described m Section 8 14... 

Section 8 14 Nucleophilic substitution can occur with leaving groups other than halide Alkyl p toluenesulfonates (tosylates) which are prepared from alcohols by reaction with p toulenesulfonyl chloride are often used... 

If the temperature is not kept below 25°C dunng the reaction of primary alcohols with p toluenesulfonyl chloride in pyndine it is sometimes observed that the isolated product is not the desired alkyl p toluenesulfonate but is instead the corresponding alkyl chlonde Suggest a mech anistic explanation for this observation... 

Conversion to p toluenesulfonate es ters (Section 8 14) Alcohols react with p toluenesulfonyl chloride to give p toluenesulfonate esters Sulfo nate esters are reactive substrates for nucleophilic substitution and elimma tion reactions The p toluenesulfo nate group is often abbreviated —OTs... 

Both reactants m the Williamson ether synthesis usually originate m alcohol pre cursors Sodium and potassium alkoxides are prepared by reaction of an alcohol with the appropriate metal and alkyl halides are most commonly made from alcohols by reaction with a hydrogen halide (Section 4 7) thionyl chloride (Section 4 13) or phosphorus tri bromide (Section 4 13) Alternatively alkyl p toluenesulfonates may be used m place of alkyl halides alkyl p toluenesulfonates are also prepared from alcohols as their imme diate precursors (Section 8 14)... 

Because halides are poorer leaving groups than p-toluenesulfonate, alkyl p-toluene-sulfonates can be converted to alkyl halides by Sn2 reactions involving chloride, bromide, or iodide as the nucleophile. 

The reaction of alcohols with acyl chlorides is analogous to their reaction with p-toluenesulfonyl chloride described earlier (Section 8.14 and Table 15.2). In those reactions, a p-toluenesulfonate ester was formed by displacement of chloride from the sulfonyl group by the oxygen of the alcohol. Carboxylic esters arise by displacement of chloride from a carbonyl group by the alcohol oxygen. 

If Y is to be a valid measure of solvent ionizing power, presumably the defining reaction should proceed via the Lim (pure SnI) process. This was the basis for the original choice of r-butyl chloride. It is now believed that /-butyl chloride sol-volyzes with some solvent participation, and modern versions of Y are based on other compounds, of which 2-adamantyl tosylate (p-toluenesulfonate, OTs), 6, is the most favored." ... 

A mixture of 200 grams of 2-benzoyloxyethanol in 2 liters of pyridine at -5°C is treated with 275 grams of p-toluenesulfonyl chloride and the resulting mixture is stirred at O C for 2 hours. Water is added slowly at O " to 5°C. Extracting with chloroform, washing the extract with dilute hydrochloric acid, water and potassium bicarbonate, and evaporating the solvent leaves benzyloxyethyl p-toluenesulfonate. 

Alternatively, the hydroxy group can be converted to the tosyl ester168 or replaced by chlorine108,169 followed by a base-catalyzed elimination. 1-Benzoxepin-5-(4//)-one is reduced with cerium(III) chloride/sodium borohydride to the hydroxy derivative. After conversion to the p-toluenesulfonate, the double bond is formed in 2 upon treatment with potassium tert-pen-toxide.168... 

The synthesis of 1-benzothiepin (7) has also been achieved, in 80% yield, by the reaction of 4,5-dihydro-l-benzothiepin-5-ol (6) with potassium hydride and -toluenesulfonyl chloride and subsequent elimination of p-toluenesulfonic acid with lerf-pentylpotassium 22... 

Attempts to prepare 5-vinyl-5F7-dibenz[b,/]azepine by alkylation of 5i/-dibenz[b,/]azepine with 2-chloroethyl-p-toluenesulfonate followed by dehydrochlorination, or by direct vinylation with acetylene under pressure in toluene or in dimethyl sulfoxide, have failed.194 Also, 5H-dibenz[b,/]azepine fails to react with acryloyl chloride, although the 5-acryloyl derivative 8 (R = COCH = CH2 mp 122 — 123 C) has been prepared in 65% yield by condensing dibenz-azepine 5 with 3-chloroacryloyl chloride, followed by dehydrochlorination of the product with l,8-diazabicyclo[5.4.0]undec-7-ene in dimethyl sulfoxide at 80-90°C.194... 

Polycondensation At room temperature, 0.4% mass of Sn(II) chloride dihydrate (SnCl2-2H20) and 0.4% mass of p-toluenesulfonic acid monohydrate (p-TSA) are introduced into the mixture. The mixture is heated to 180°C under mechanical stirring. The pressure is reduced stepwise to reach 13 mbar, and file reaction is continued for 20 h. The reaction system becomes gradually viscous, and a small amount of L-lactide is formed and refluxed through the reflux condenser. At file end of the reaction, the flask is cooled down, file product is dissolved in chloroform and subsequently precipitated into diethyl ether. The resulting white fibrous solids are filtered and dried under vacuum (average yield 67%). 

Thiol protection, 59, 190 Thiono esters, reaction with ethyl isocyanoacetate, 59,187 Thionyl chloride, 55, 27 Thiophenol, 55, 122 58, 144 Thorium dodecanedioate, 56,110 Toluene, 56, 86 58,125 p-Toluenesulfonates, reaction with organo-cuprates, 55,112 p-Toluenesulfonic acid, 58, 57, 63 p-Toluenesulfonic acid, monohydrate, 56,44... 

Enolizahon of cyanoketone rac-5 under the previously optimized conditions, followed by reaction with p-toluenesulfonic anhydride afforded a 90 10 ratio of the two expected enol tosylates in 90% yield. An immediate advantage of the tosylates compared to the triflate was seen on isolation, when the desired compound 32 was found to be a crystalline solid. In this way an 85% isolated yield of 32 as a single isomer could be achieved without the need for chromatography (Scheme 9.24). Use of p-toluenesulfonyl chloride in place of the anhydride led to a-chlorination... 

Epiberberine and berberine were stereoselectively converted to fumaritrine (421) and its analog via 8,14-cycloberbines 216). The cycloberbine 432, derived from epiberberine (431) in the established way, was treated with p-toluenesulfonic acid in methanol and then with methyl iodide to give stereoselectively the cis-fused indenobenzazepine 433 in excellent yield (Scheme 86). Deoxygenation of the hydroxyl group in 433 was accomplished by treatment with methanesulfonyl chloride and subsequent reduction with sodium borohydride in dimethoxyethane to give (+ )-fumaritrine (421) (216). 

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