Acetic acid esters from

Sundberg, R. J., Lin, L. S., and Smith, F. X., Photochemical deconjugation as a synthetic route to l,2,3,6-tetrahydropyridine-4-acetic acid esters from A > -piperidine-4-acetic acid esters, /. Org. 

Bornyl Acetate.—The acetic acid ester is the most important of the series. It is a constituent of pine-needle and rosemary oils, and has a most fragrant and refreshing odour. It is prepared artificially by the action of acetic anhydride on borneol, in the presence of sodium acetate, or by the condensation of borneol with glacial acetic acid in the presence of a small amount of a mineral acid. It is absolutely necessary in the reproduction of any pine odour. It is a crystalline body, crystallising from peDroleum ether in rhombic hemihedric crystals melting at 29°. The optical activity depends on that of the borneol from which it has been prepared. It has the following characters —... 

For the synthesis of permethric acid esters 16 from l,l-dichloro-4-methyl-l,3-pentadiene and of chrysanthemic acid esters from 2,5-dimethyl-2,4-hexadienes, it seems that the yields are less sensitive to the choice of the catalyst 72 77). It is evident, however, that Rh2(OOCCF3)4 is again less efficient than other rhodium acetates. The influence of the alkyl group of the diazoacetate on the yields is only marginal for the chrysanthemic acid esters, but the yield of permethric acid esters 16 varies in a catalyst-dependent non-predictable way when methyl, ethyl, n-butyl or f-butyl diazoacetate are used77). 

Like in Chapt. 7, we begin the discussion with acetates, since acetic acid is the simplest nontoxic acyl group, formic acid being less innocuous. An informative study was carried out to compare the kinetics of hydrolysis of two types of corticosteroid esters, namely methyl steroid-21-oates (which are active per se) and acetyl steroid-21-ols (which are prodrugs), as exemplified by methyl prednisolonate (8.69) and prednisolone-21-acetate (8.70), respectively [89]. In the presence of rat liver microsomes, the rate of hydrolytic inactivation of methyl steroid-21-oates was much slower than the rate of hydrolytic activation of acetyl steroid-21-ols. Thus, while the Km values were ca. 0.1 -0.3 mM for all substrates, the acetic acid ester prodrugs and the methyl ester drugs had Vmax values of ca. 20 and 0.15 nmol min-1 mg-1, respectively. It can be postulated that the observed rates of hydrolysis were determined by the acyl moiety, in other words by the liberation of the carboxylic acid from the acyl-enzyme intermediate (see Chapt. 3). 

Acetates are esters of acetic acid. Remember from Chapter 1 that an ester has a signature group... 

Figure 3. 3,5-Dinitrobenzoic acid esters from transesterification of some plasticizers Kieselgel G Eluent benzene,methyl acetate (150 1 pt. by vol.)...

Fig. 19. HjOj oxidation of l-propanol catalyzed by TS-1. (A) Acid, (+) aldehyde, ( ) acetal, (O) ester. (From Romano ei al., 1990.)...

Enantiopure fused oxopiperazino-/3-lactams have been produced by application of the Staudinger reaction with 5,6-dihydropyrazin-2-(l/7)-ones and the /3-lactams were converted to the 2-oxopiperazine-3-acetic acid esters in good yield with no epimerization (Equation 86) <2006TL8911>. Fused /3-lactams have been formed from macrocyclic imines by use of the Staudinger reaction (see Section 2.04.9.7). When phenoxyacetyl chloride and triethylamine were used, the best yields (45-52%) of the fused /3-lactams were obtained with dry dichloromethane as solvent <2006TL8855>. 

The phenyl acetic acid esters are highly valuable intermediates for a lot of applications. Among them, they are applied for the synthesis of fragrances e.g. ethyl ester (honey odour), isobutyl ester (sweet roses odour). The present industrial process for phenyl acetic esters starts from benzylchloride and uses the reactions with KCN to form benzylcyanide 7 (Eq. 15.2.4) and followed by hydrolytic cleavage. 

On the basis of these results, we have developed the first method for the enantiose-lective synthesis of chiral /3-amino acid esters from achiral imines and ketene silyl acetals using BLA 28. The enantioselectivity of the aldol-type reaction is dramatically increased by using sterically bulky A-substituents. Condensation of the imine derived from benzhydrylamine occurs with high enantioselectivity (90 % ee) (Eq. 80). Furthermore, the best result (96 % ee) is achieved by use of a 1 1 (v/v) mixture of toluene and dichloromethane as solvents. Thus, excellent enantioselectivity (95 % ee or better) has been achieved in reactions of aromatic aldehyde-derived imines... 

Reaction of 3-bromo-7-azabicyclo[2.2.1]hepta-2,5-dienecarhoxylic esters 1229 with 2-amino- or 2-aminomethyl-anilines 1230 produces r-5-(benzimidazol-2-yl)pyrroline-2-acetic acid esters 1231 from a double Michael addition process. Substituents on the nitrogen atoms or in the aromatic ring are tolerated as long as they do not strongly reduce the nucleophilicity of the nitrogen atoms (Scheme 307) <2005S2357>. 

From Menthane.— Taking up these compounds in the same order in which we considered the terpenes themselves we have first the alcohols and ketones derived from menthane, the saturated mono-cyclic terpene. The more common alcohol is known as menthol, menthanol or terpanol and the corresponding ketone is named similarly menthone, menthanone or terpanone. Both of these compounds are present in Japanese, Russian and American peppermint oil the former occurring both as the free alcohol and as the acetic acid ester. Menthol is a crystalline solid, m.p. 42°, b.p. 213°. It has the characteristic peppermint odor and is used as a disinfectant and as a mild anesthetic for headache. Menthone is a liquid, b.p. 207°. The constitution of both compounds is proven by their relationship to thjrmol, i-methyl 3-... 

Recently, 6-hydroxydihydrosanguinarine (34) has been reported as a new alkaloid isolated from Dactylicapnos torulosa Hook f et Thoms. [125,126]. The compound is described as an amorphous solid of yellow colour, however, the substance e diibits major discrepancies in ipectral data with the structure given [127]. 6-Hydroxydihydrochelerythrine has allegedly been isolated from Toddalia aculeata Pers. in the form of its acetic acid ester [128], However, its H NMR data are not in agreement with those previously published for this compound [129]. Universally, 6-hydroxydihydroderivatrves (pseudobases) are unstable semiaminoacetals with basic character which cannot occur in acidic plant tissues at all and could not be isolated as natural products especially after 5% HCl has been used in the isolation procedure cf. 125,128]. 

Pyrolysis of cellulose acetate has been applied for analytical purposes of the fibers [44], structural elucidation [45], study of thermal stability [46], etc. The main pyrolysis product of cellulose acetate is acetic acid. Several compounds typical in cellulose pyrolysis such as 5-hydroxymethyl-2-furancarboxaldehyde can be seen as its ester with acetic acid. Also, some compounds tentatively identified as dihydroxydioxanes and dihydroxydioxolanes in cellulose pyrolysate are found as acetic acid esters in the pyrolysate of cellulose acetate. Depending on the degree of substitution (D.S.), for D.S < 3, free -OH groups are still present in cellulose. This allows the formation of compounds typical for cellulose pyrolysate in addition to the compounds resulting from... 

Its inactivity gives preference to the second formula the first, however, contains an asymmetric carbon atom, for which reason I hope to be able to produce the acid named by following the method of Frankland and Duppa from oxalic acid and iodo acetic acid esters by the aid of zinc. 

Aryl-substituted ketones react directly with elemental sulfur in hexa-methylphosphorus triamide with formation of l,2-dithiole-3-thiones.46,47 Aryl-substituted acetaldehydes can condense likewise with carbon disulfide to give the analogous 4-aryl-substituted l,2-dithiole-3-thiones.48 The same reaction was observed with aryl-substituted acetic acid esters, in which a methylthio group is incorporated into the reaction product (26).49 Thioketones and enthioles react analogously. 50,51 The parent l,2-dithiole-3-thione (27) has been prepared from the tetra-methyl acetal of malondialdehyde and phosphorus pentasulfide.52 In the presence of ammonia the reaction of cyclohexanone or cycloheptanone with carbon disulfide and sulfur gives as by-products the condensed 1,2-dithiole-3-thiones 28a and 28b, respectively.53... 

Increasing the temperature to 350 °C results in decarbonylation of the phenylpyruvic acid methyl ester derivatives and the phenyl acetic ester is formed with a ratio of 65 % a-ketoester to 35 % acetic acid ester. Until now the industrial process for the synthesis of phenylacetic acid ester has started from benzyl chloride, which is converted to benzyl cyanide by KCN, followed by hydrolysis. Every step of this reaction must be performed in a separate reactor and special measures must be taken for handling large amounts of toxic KCN. The new route is certainly an environmentally benign alternative [8,27]. 

---