J>-Toluenesulfonic acid

As basic catalysts KOH, NaOH or piperidine are used. As acidic catalysts are used HCl, H2SO4, polyphosphoric acid or /j-toluenesulfonic acid. 

A mixture of cyclohexanone (11.8 g, 0.12 mole), ethylene glycol (8.2 g, 0.13 mole), /j-toluenesulfonic acid monohydrate (0.05 g), and 50 ml of benzene is placed in a 250-ml round-bottom flask fitted with a water separator and a condenser (drying tube). The flask is refluxed (mantle) until the theoretical amount of water (approx. 2.2 ml) has collected in the separator trap. The cooled reaction mixture is washed with 20 ml of 10 % sodium hydroxide solution followed by five 10-ml washes with water, dried over anhydrous potassium carbonate, and filtered. The benzene is removed (rotary evaporator) and the residue is distilled, affording l,4-dioxaspiro[4.5]decane, bp 65-67713 mm, 1.4565-1.4575, in about 80% yield. 

The reaction of 20 g (0.177 mole) of 1,3-cyclohexanedione (Chapter 5, Section II) with 21.8 g (0.22 mole) of maleic anhydride and 0.1 g of/j-toluenesulfonic acid in 150 ml of isopropenyl acetate is conducted as described above to give about 70% of the recrystallized product, mp 156-159°. 

The p-toluenesulfonyl chloride should be free of j-toluenesulfonic acid, otherwise potassium p-toluenesulfonate will be formed and will result in the formation of tosylates, rather than thiotosylates. The reagent used by the checkers was obtained from British Drug Houses Ltd. and was purified according to the following procedure.4 A benzene solution of the tosyl chloride was washed with 5% aqueous sodium hydroxide, dried with magnesium sulfate, and then distilled under reduced pressure, b.p. 146° (15 mm.). 

Acid- or base-catalyzed retro-aldolization of protected 7-hydroxybicyclo[5.2.0]nonane-l-carb-oxylates afforded bridged cyclononanone derivatives.14 Methyl esters were found in the /j-toluenesulfonic acid catalyzed reaction in refluxing methanol to give la and 2, whilst the free acid lb was formed with potassium hydroxide.14... 

A useful synthesis of benzo[c]furans, based on experiments described by Ried, has been published by White et It consists of the Diels-Alder reaction of an acyclic diene with dibenzoylacetylene (146) and subsequent ring closure of the resulting 1,2-diaroylcyclohexadiene with /j-toluenesulfonic acid in benzene there has, however, been one report where this... 

Heteropolyacids catalyze the Prins reaction of alkenes [Eq. (14)] more efficiently than H2SO4 and /j-toluenesulfonic acid (PTS). For example, H3PW12O40 is 10-50 times more active than H2S04 or PTS (162). In this reaction, oxocarbo-cations may be stabilized through complexation with heteropolyanions ... 

Povarov has reported that the addition of ethyl- 1-cyclohexenyl ether to benzylideneaniline and a number of its derivatives in the presence of boron trifluoride etherate provides the adducts (171a-d). 171a can be converted into 6-phenyl-7,8,9,I0-tetrahydrophenanthri-dine either by treatment with /j-toluenesulfonic acid or oxidation with potassium permanganate.200... 

Benzoxathiin and benzodithiin derivatives can also be derived as rearrangement products of other heterocyclic rings. Thus, nonstereospecific ring expansion reactions of 1,3-benzoxathiole sulfoxides (210) and 1,3-benzodithiole sulfoxides (211) with acetic anhydride or /j-toluenesulfonic acid afford the corresponding 1,4-benzoxathiins or 1,4-benzodithiins (212) and (213) in satisfactory yields... 

Aryl-5-tosyloxyhexanoates are converted to mixtures of lactones when exposed to silica or heated with /j-toluenesulfonic acid in various solvents. The aryl ring must have an EWG for the reaction to proceed. A similar reaction occurs with 4-aryl-5-tosyloxypentanoates, but in this case only y-lactones are formed. Suggest a mechanism that accounts for both the observed regioselectivity and stereoselectivity and the requirement for an ERG on the aryl ring. 

Long-chain symmetrical ethers can also be prepared from the alcohols by using /j-toluenesulfonic acid 667 boiling 2,2 -thiodiethanol (thiodiglycol) with isopentyl alcohol and /Koluenesulfonic acid under reflux for 4 hours gives an 83% yield of the diisopentyl ether 668... 

Refluxing tinoleic acid and a primary or secondary alkyl amine with j )-toluenesulfonic acid in toluene for 8—18 h also yields the substituted amides (32—34). The reaction of methyl esters with primary or secondary amines to make substituted amides is catalyzed with sodium methoxide. Reactions are rapid at 30°C under anhydrous conditions (35). Acid chlorides can also be used. N,N-dibutyloleamide [5831-80-1been prepared from oleoji chloride and dibutyl amine (36). 

Sieskind and Albrecht (1985) showed that cholestene underwent a backbone rearrangement in the presence of montmorillonite at room temperature in cyclohexane to give an almost quantitative yield of the product (Equation 7.7). The same isomer had 2ilso been obtained, in 50% yield, in the absence of clay by refluxing cholestene in acetic acid in the presence of /J-toluenesulfonic acid. Dry bentonite or kaolinite... 

To a solution of 31.84 g (0.159 mole) of 3,9-bis (ethylidene)-2,4,8,10-tetraoxaspiro [5,5] undecane in 200 mL of distilled tetraliydrofuran is added 10.42 g (0.100 mole) of 2-methyl-l,4-butanediol. The solution is stirred under argon and 0.5 mL of j -toluenesulfonic acid solution in tetrahydrofuran (20 mg/ml) is added to initiate the reaction. After the heat of reaction has subsided, the solution is stirred until the temperature returns to ambient and then concentrated on a rotary evaporator followed by heating in a vacuum oven at 40° C to remove residual solvent. 

Under anhydrous conditions, 1,1,4-cyclohexanetrimethanol (3.524 g, 20 mmoles), trimethyl orthoacetate (2.403 g, 20 mmoles), J toluenesulfonic acid ( 3 mg) and distilled cyclohexane (80 mL) were added to a pre-dried flask. The flask was fitted with a spinning band column and heated at 100°C under argon. Methanol was removed azeotropically at 56°C at a fast rate and as the boiling point began to rise, the distillation rate was reduced to 4 drops/min. and heating continued for 15 hrs. The polymer thus prepared precipitated out of cyclohexane. The powdery pol)Tner is cr stalline with a melting point (DSC) of 212°C. It is insoluble in the usual organic solvents such as methylene chloride, chloroform, ether, tetrahydrofuran, ethyl acetate, acetone, dimethylformamide, and dimethylsulfoxide. 

Scheme 3 Initial rates for reagents 1, 2, and 7 in the trifluoromethylation of /j-toluenesulfonic acid [1, 9-12]...

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