Sulfonic acid esters acetals

Because carbohydrates are so frequently used as substrates in kinetic studies of enzymes and metabolic pathways, we refer the reader to the following topics in Ro-byt s excellent account of chemical reactions used to modify carbohydrates formation of carbohydrate esters, pp. 77-81 sulfonic acid esters, pp. 81-83 ethers [methyl, p. 83 trityl, pp. 83-84 benzyl, pp. 84-85 trialkyl silyl, p. 85] acetals and ketals, pp. 85-92 modifications at C-1 [reduction of aldehydes and ketones, pp. 92-93 reduction of thioacetals, p. 93 oxidation, pp. 93-94 chain elongation, pp. 94-98 chain length reduction, pp. 98-99 substitution at the reducing carbon atom, pp. 99-103 formation of gycosides, pp. 103-105 formation of glycosidic linkages between monosaccharide residues, 105-108] modifications at C-2, pp. 108-113 modifications at C-3, pp. 113-120 modifications at C-4, pp. 121-124 modifications at C-5, pp. 125-128 modifications at C-6 in hexopy-ranoses, pp. 128-134. 

Besides ordinary halides and sulfonic acid esters, the development of transition metal catalyzed processes has enabled allylic alcohols, acetates, carbonates, vinyl epoxides and vinyllactones also to be successfully employed as allylic substrates. 

Solid esters are easily crystallisable materials. It is important to note that esters of alcohols must be recrystallised either from non-hydroxylic solvents (e.g. toluene) or from the alcohol from which the ester is derived. Thus methyl esters should be crystallised from methanol or methanol/toluene, but not from ethanol, n-butanol or other alcohols, in order to avoid alcohol exchange and contamination of the ester with a second ester. Useful solvents for crystallisation are the corresponding alcohols or aqueous alcohols, toluene, toluene/petroleum ether, and chloroform (ethanol-free)/toluene. Esters of carboxylic acids derived from phenols are more difficult to hydrolyse and exchange, hence any alcoholic solvent can be used freely. Sulfonic acid esters of phenols are even more resistant to hydrolysis they can safely be crystallised not only from the above solvents but also from acetic acid, aqueous acetic acid or boiling n-butanol. Note that sulfonic esters of lower alcohols, e.g. methanol, are good alkylating agents. 

Adipic acid Butyl alcohol N-Hydroxysuccinic acid Isoborneol Isostearic acid PEG-6 acrylate PEG-9 acrylate Perchloric acid Succinic anhydride Xylene sulfonic acid ester mfg., flavoring n-Butyric acid ester mfg., flavoring agents Isobutyric acid Phenylacetyl chloride ester mfg., fragrances n-Butyric acid ester mfg., perfume bases Isobutyric acid ester mfg., plasticizers PPG-2 methyl ether ester mfg., solvents Isobutyric acid ester modifier Dimethyloctanyl acetate ester oil mfg., complex Isooctanoic acid ester synthesis Isocetyl alcohol... 

Besides acetates and benzoates many other types of carboxylic acid esters can be formed, such as chloroacetates, trifluoroacetates, pivalates, carbonates, and thiocarbonates, by reaction with chloroacetic anhydride, trifluoroacetic anhydride, pivaloyl chloride (2,2-dimethyl propanoyl chloride), phosgene or methylchloro-formate, and carbon disulfide or carbonyl sulfide, respectively. Each of the ester derivatives imparts specific chemical properties to the carbohydrates so they can be used selectively in synthetic schemes. It was found that the sulfonic acid esters... 

After having been washed with 50 cc of water the benzene layer is dried over potassium carbonate, filtered, allowed to stand over 10 g of alumina for about VA hours for partial decolorization, filtered again and concentrated under reduced pressure. The oily base which remains as a residue is directly converted into the tartrate. A solution cooled to 0°C, of 6.50 g of the free base in 100 cc of acetic acid ethyl ester is thoroughly shaken and poured into an ice cold solution of 2.66 g of tartaric acid in 410 cc of acetic acid ethyl ester. The precipitated, analytically pure, tartrate of 3-methylsulfinyl-10-[2 -N-methyl-piperidyl-2")-ethyl-1 ]-phenothiazine melts at 115° to 120°C (foam formation) and sinters above B0°C. The base Is reacted with benzene sulfonic acid in a suitable solvent to give the besylate. 

The reaction of alcohols with CO was catalyzed by Pd compounds, iodides and/or bromides, and amides (or thioamides). Thus, MeOH was carbonylated in the presence of Pd acetate, NiCl2, tV-methylpyrrolidone, Mel, and Lil to give HOAc. AcOH is prepared by the reaction of MeOH with CO in the presence of a catalyst system comprising a Pd compound, an ionic Br or I compound other than HBr or HI, a sulfone or sulfoxide, and, in some cases, a Ni compound and a phosphine oxide or a phosphinic acid.60 Palladium(II) salts catalyze the carbonylation of methyl iodide in methanol to methyl acetate in the presence of an excess of iodide, even without amine or phosphine co-ligands platinum(II) salts are less effective.61 A novel Pd11 complex (13) is a highly efficient catalyst for the carbonylation of organic alcohols and alkenes to carboxylic acids/esters.62... 

Alternatively, dissolve 220 g 4-benzyloxy-3-indoleacetic acid (or equimolar amount other indoleacetic acid) in 2 L absolute methanol and reflux six hours in the presence of 20 g Dowex 50X8 sulfonic acid resin. Filter (decolor with carbon if desired) and concentrate below 35° until precipitation starts then cool to precipitate and filter to get 200 g of the methyl ester. Add 200 g of the ester to 600 ml 40% aqueous methylamine over twelve hours with vigorous stirring. Filter, wash precipitate with water and dry to get 187 g of the N-methyl-acetamide (reflux two hours in 500 ml benzene to remove unreacted ester). 24 g of the acetamide in 300 ml tetrahydrofuran is added dropwise to 10 g lithium aluminum hydride in 300 ml tetrahydrofuran reflux ten hours, cool to 15° and add dropwise with stirring 50 ml ethyl acetate. Reflux two hours and proceed as above to get 15 g (II) or analog. 

Mannitol hexanitrate is obtained by nitration of mannitol with mixed nitric and sulfuric acids. Similarly, nitration of sorbitol using mixed acid produces the hexanitrate when the reaction is conducted at 0—3°C and at —10 to —75°C, the main product is sorbitol pentanitrate (117). Xylitol, ribitol, and L-arabinitol are converted to the pentanitrates by fuming nitric acid and acetic anhydride (118). Phosphate esters of sugar alcohols are obtained by the action of phosphorus oxychloride (119) and by alcoholysis of organic phosphates (120). The 1,6-dibenzene sulfonate of D-mannitol is obtained by the action of benzene sulfonyl chloride in pyridine at 0°C (121). To obtain 1,6-dimethanesulfonyl-D-mannitol free from anhydrides and other by-products, after similar sulfonation with methane sulfonyl chloride and pyridine the remaining hydroxyl groups are acetylated with acetic anhydride and the insoluble acetyl derivative is separated, followed by deacetylation with hydrogen chloride in methanol (122). Alkyl sulfate esters of polyhydric alcohols result from the action of sulfur trioxide—trialkyl phosphates as in the reaction of sorbitol at 34—40°C with sulfur trioxide—triethyl phosphate to form sorbitol hexa(ethylsulfate) (123). 

The mixture of the (R)-HMPC and the (S)-acetate 4 from the enzymatic hydrolysis was esterified with methanesulfonyl choride and triethylamine to afford a mixture of the corresponding (R)-sulfonate 5a and the (S)-acetate 4. The (S)-acetate 4 was unaffected by the sulfonation conditions. The resultant mixture of two esters, 4 and 5a, was hydrolyzed in the presence of a small amount of calcium carbonate. The (R)-sulfonate 5a was converted into the (S)-HMPC 6 as a result of inversion of configuration. On the other hand, the (S)-acetate 4, was hydrolyzed with retention of configuration. Consequently, all of the racemic acetate J3, was converted with maximum efficiency to the desired (S)-HMPC 6, by the sequence enzymatic hydrolysis and sulfonation followed by inversion of the chiral center in (R)-HMPC without separation of the (S)-acetate Similar transformations could also be carried out via nitrate ester intermediate 5b obtained from the reaction of the (R)-HMPC with nitric acid and acetic anhydride. 

The hydrazine (340) and acetic anhydride give the pyrazolopyrimidine (341 R = Me). With mixed formic-acetic anhydride the unsubstituted derivative (341 R = H) is obtained (58LA(615)42). The pyridylacetic ester (342) reacts with hydroxylamine-O-sulfonic acid in water at room temperature to give the phenolic compound (13) (see Section 4.05.2.4) (76BCJ1980). 

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