Chlorophenyl-acetate

The DKR of secondary alcohols can be efficiently performed via enzymatic acylation coupled with simultaneous racemization of the substrates. This method was first used by BackvaU for the resolution of 1-phenylethanol and 1-indanol [38]. Racemization of substrate 18 by a mthenium catalyst (Scheme 5.11) was combined with transesterification using various acyl donors and catalyzed by C.antarctica B Hpase. From aU the acyl donors studied, 4-chlorophenyl acetate was found to be the best. The desired product 19 was obtained in 80% yield and over 99% ee. 

Markus A, D Krekel, E Lingens (1986) Purification and some properties of component A of the 4-chlorophenyl-acetate 3,4-dioxygenase from Pseudomonas species strain CBS. J Biol Chem 261 12883-12888. 

This reaction was applied to a mixture of diastereoisomeric diols [113], For instance, a,cx -dimethyl-l,4-benzenedimethanol was treated with Ru complex 30 (S/C=25), Novozyme 435, and 4-chlorophenyl acetate (3 equiv) in toluene at 70 °C to give the R,R diacetate in >99% ee and the meso isomer (R,R meso=98 2) in 77% yield (Scheme 40). Reaction of 1,3-pentanediol and 1,4-hexanediol gave the corresponding R,R diacetate in >99% ee, while the R,R to meso ratio was lower than that of the aromatic diacetate. Nitrogen-containing substrates also gave the desired products in optically pure form. 

Ru complex 46 [333b,334]. 4-Chlorophenyl acetate is a suitable acetyl donor because the produced 4-chlorophenol does not interfere with the catalytic racemization. 

The H202-HF-SbF5 system has been applied by Jacquesy and co-workers in the hydroxylation of a variety of functionalized arenes.624 Hydroxylation of phenyl esters has been shown to afford themeta and para isomers as main products625 [Eq. (5.217)]. Substantial amounts of the deacylated derivatives were obtained in the reaction of phenyl formate and diphenyl carbonate. In the hydroxylation of 2-chlorophenyl and 4-chlorophenyl acetate, regioselectivity is controlled by the chlorine substituent with the hydroxyl entering into the meta position to the ester group.626 A similar effect was observed in the hydroxylation of anilines and anilides. 

Racemic resolution of a-hydroxy esters was achieved with Pseudomonas cepacia lipase (PCL) and a ruthenium catalyst (for a list, see Figure 18.13) as well as 4-chlorophenyl acetate as an acyl donor in cyclohexane, with high yields and excellent enantiomeric excesses (Huerta, 2000) (Figure 18.14). Combining dynamic kinetic resolution with an aldol reaction yielded jS-hydroxy ester derivatives in very high enantiomeric excesses (< 99% e.e.) in a one-pot synthesis (Huerta, 2001). 

The same concept is applicable to allylic alcohols, ketones, or ketoximes. Enol acetates or ketones were successfully converted in multi-step reactions to chiral acetates in high yields and optical yields through catalysis by Candida antarctica lipase B (CALB, Novozyme 435) and a ruthenium complex. 2,6-Dimethylheptan-4-ol served as a hydrogen donor and 4-chlorophenyl acetate as an acyl donor for the conversion of the ketones (Jung, 2000a). 

A solution of 19.2 g (0.096 mole) of a-methoxy-4-chlorophenyl acetic acid in 200 ml of acetone is cooled in an ice bath to 0°C. To the cooled solution is added 10.2 g (0.1 mole) of triethylamine in 100 ml of acetone. The temperature of the reaction mixture is maintained at 10°C and a solution of 11.0 g (0.1 mole) of ethylchloroformate in 45 ml of acetone is added dropwise with agitation so as to maintain a final reaction temperature of -5°C. To this mixture is then slowly added with stirring a solution of 23.8 g (0.11 mole) of 6-aminopenicillanic acid in 40 ml of water and 15 ml of triethylamine. Upon completion of the addition, the mixture is stirred while attaining room... 

ETHYL-2 (HYDROXY-4 BENZOYL)-3 BENZOFUKANNE see BBJ500 ETHYL-2-HYDROXY-2,2-BIS(4-CHLOROPHENYL)ACETATE see DEROOO N-ETHYL-N-(2-HYDROXYETHYL)-3-METHYL-4-NITROSOANILINE see ELGIOO ETHYL-2-HYDROXYETHYI-NITROSAMINE see ELG500... 

The equilibrium constant for formation of 4-chlorophenyl acetate from 4-chlorophenolate ion and acetyl 4-methylpyridinium ion is given by ... 

An alternative enzyme/transition metal combination employs transfer hydrogenation catalysts that are capable of racemizing secondary alcohols. The racemization procedure temporarily converts the alcohol into an achiral ketone, which is reduced back to the racemic alcohol. Coupling this racemization procedure to an enzyme-catalyzed acylation reaction affords a dynamic resolution process (Fig. 9-12). Several enzyme/transition metal combinations have been shown to be effective for these reactions, although ruthenium complexes 1-3 appear to be especially effective for the in situ racemization of the alcohol. The product esters are not prone to racemization under the reaction conditions. Early results employing transfer hydrogenation catalysts to effect the racemization of alcohols required the use of added ketone 21, 22. However, it was subsequently shown that added ketone was not required when appropriate transition metal complexes were used as catalysts. Furthermore, the use of 4-chlorophenyl acetate as the acyl donor afforded improved results. 

The fates of the herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) 2, 4, 5-trichlorophenoxyacetic acid (2,4,5-T) and the DDT metabolite, bis-(4-chlorophenyl) acetic acid (DDA) were studied in the spiny lobster, Panulirus argus 24). All acids were injected intrapericardially at 10 mg/kg. Both 2,4-D or 2,4,5-T were extensively excreted, unchanged, in urine in the first 24 hours after the dose. About 10% of the dose of 2,4,D and 2,4,5T was taken up by hepatopancreas where the taurine conjugate was formed and subsequently excreted either in urine or feces. Part of the DDA dose was excreted in urine, as unchanged DDA and as DDA-taurine, but DDA was more extensively taken up by shell and hepatopancreas and more slowly excreted than 2,4D or 2,4,5-T. For all three carboxylic acids, muscle concentrations were lower than hemolymph concentrations at 24 hours after the dose, and were less than 5p.g/g. 

James MO (1982) Disposition and taurine conjugation of 2,4-dichlorophenoxyacetic acid, 2,4,5-trichlorophenoxyacetic acid, )/5(4-chlorophenyl)acetic acid, and phenylacetic acid in the spiny lobster, Panulirus argus. Drug Metab Disp 10 516-522 James MO (1984) Catalytic properties of cytochrome P-450 in hepatopancreas of the spiny lobster, Panulirus argus. Mar Env Res 14 1-11... 

Another important derivative of m-cresol used in the manufacture of plant protection agents is m-phenoxytoluene, which can be produced from m-cresol and chloro- or bromobenzene at temperatures of 200 °C, with copper catalysts. m-Phenoxytoluene is converted into m-phenoxybenzoic acid methyl ester by oxidation with a cobalt acetate/KBr catalyst and subsequent esterification m-phenoxybenzoic add methyl ester serves as an intermediate in the production of m-phenoxybenzaldehyde, which is used as the raw material in the production of the synthetic pyrethroid insecticide, fenvalerate (see Chapter 6.3.2). The cyanohydrin is formed in-situ, then made to react with 2-isopropyl-(4-chlorophenyl) acetic acid chloride to yield fenvalerate, which was developed by Sumitomo Chemical in 1972. Pyrethroid insecticides are distinguished by their low toxicity and high activity. 

Synonyms Acar Acaraben Acaraben 4E Akar Akar 50 Akar 338 Benzilan Benz-o-chlor Chlorbenzilat Chlorbenzilate Chlorobenzylate Compound 338 4,4 -Dichloroben-zilate 4,4 -Dichlorobenzilic acid ethyl ester ENT 18596 Ethyl 4-chloro-a-(4-chlorophe-nyl) -a-hydroxybenzene acetate Ethyl-4,4-dichlorobenzilate Ethyl-p,/> -dichlorobenzi-late Ethyl-4,4 -dichlorodiphenyl glycollate Ethyl-p,y-dichlorodiphenyl glycollate Ethyl-2-hydroxy-2,2-bis(4-chlorophenyl)acetate Folbex Folbex smoke-strips G 338 G 23,992 Geigy 338 Kop-mite NCI-C00408 NCI-C60413 RCRA waste number U038. 

N,N-Dimethylamino) -2-dissolved in coned. H2SO4, stirred 3 hrs., water added to reduce the acid concentration to ca. 70%, and heated 18 hrs. at 150° with stirring 2-(N,N-dimethyl-amino) -2- (4-chlorophenyl) acetic acid. 

The metabolism of DDT 355), and presumably its analogues 356, 357, 393), involves a series of reductive dechlorinations and dehydrochlorina-tions/ Buselmaier et have reported that DDD is mutagenic with Ser-ratia marcescens but not with Salmonella strain G46 in the host-mediated assay DDT, DDE, and DDA [di(4-chlorophenyl)acetic acid] were not positive in similar testing. 

Preparation by Fries rearrangement of 2-bromo-4-chlorophenyl acetate with aluminium chloride without solvent at 140° [1793]. 

Preparation by Fries rearrangement of 4-chlorophenyl acetate with aluminium chloride without solvent between 110° and 200° [1837,1851,1867,1871,1947,1965,1967, 1970,1994,1998,2008-2014], (90-100% yield)... 

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