Propionic acid ester

Bornyl Propionate.—The propionic acid ester of borneol closely resembles the acetic ester, but as is, of course, usual in homologous series, its odour is slightly different. It has the formula... 

Cinnamyl Propionate.—The propionic acid ester has a distinct grapelike odour, and is very useful for fruit and flower blends. It has the constitution. CH CH. CH,OOC. CH,. CH,. 

In the second method (Scheme 26) a 3-oxo ester is synthesized from an acid chloride and 2,2-dimethyl-l,3-dioxane-4,6-dione. Then, reductive amination of the 3-oxo ester with a-methyl(phenyl)methylamine provides a 3-amino- 3-alkyl propionic acid ester. This compound is then converted into the corresponding aldehyde, which is condensed with an eno-late to afford the final product. A representative synthetic procedure of this method is given in detail. 

Deprotonation of OJ-alkylated acetic acid esters (e. g., the propionic acid ester of Figure 13.16) with LDA at-78 °C selectively yields the "if "-enolates. The quotation marks indicate that this application of the term is based on an extension of the /f/X-n omencIature here, the Cahn-Ingold-Prelog priority of the 0 Li substituent is considered to he higher than the priority of the OR group. The deprotonation of the ester shown in Figure 13.16 occurs via the strain-free transition state A. The alternative transition state B is destabilized by a 1,3-diaxial interaction. 

Side Note 13.4 presents the diastereoselective alkylation of a very special ester enolate in which one can easily understand what the stereocontrol observed is based upon. However, only very specific carboxylic acid derivatives are made accessible by those alkylations. Much more broadly applicable diastereoselective alkylations of chiral ester or amide enolates will be introduced in Figures 13.42 and 13.43. Figure 13.42 shows alkylations of a propionic acid ester—derived from an enantiomerically pure chiral alcohol—via the and Z -enolate. 

Fig. 13.42. Helmchen synthesis of enantiomerically pure a-alkylated carboxylic acids. The deprotonation of the propionic acid ester results in the "f "-enolate in the solvent THF and in the "Z"-enoLate in the solvent mixture THF/HHPA. In these projections, both enolates react preferentially from the front. The "f" -enolate results in a 97 3 mixture of 5- and fi-configured a-benzyl-propionic acid esters (X marks the chiral alkoxide group), while the "Z"-enolate results in a 5 95 mixture. Chromatographic separation and reduction of the C(=0)—Xc groups afford alcohol B with 100% ee from the " "-enolate and alcohol ent-B with 100% ee from the "Z"-enolate.

Figure 14.51 shows four Ireland-Claisen rearrangements that exhibit simple diastereose-lectivity (see Section 11.1.3 for a definition of the term). The substrates are two cis, trans-iso-meric propionic acid esters. The propionic acid esters in Figure 14.51 are derived from achiral allyl alcohols. This is different from the situation in Figure 14.50. However, these esters contain a stereogenic C=C double bond. Both the esters in Figure 14.51 can be converted into their 7 "-enolates with LDA inpureTHF (cf. Figure 13.16). Silylation affords the two T -con-figured O-allyl-O-silyl ketene acetals A and D, respectively. Alternatively, the two esters of Figure 14.51 can be converted into their Z -enolates with LDA in a mixture of THF and DMPU (cf. Figure 13.17). Treatment with rert-BuMe,SiCl then leads to the Z-isomers B and C of the O-allyl-O-silyl ketene acetals A and D, respectively.

NCA a-[18F]Fluoro-substituted acetic and propionic acid esters have been obtained169 by aminopolyether (APE 2.2.2) supported nucleophilic exchange as shown in equation 76 and applied169 for NCA 18F-fluoroacylation of ethanol (equation 77) and of -butylamine (equation 78). The above reactions are relevant to 18F-labelling of biomolecules such as peptides170. 

Although tryptophan does not dissolve in benzene, 3-indole-propionic acid ester (ft =CH3 C6H13) is soluble in benzene, and converts smoothly to the corresponding 2 -formamidophenyl-... 

The situation changes when chiral ester enolates or chiral amide enolates are alkylated. There, the half-spaces on the two sides of the enolate planes of the substrates are diastereotopic, and alkylating reagents can attack from one of the sides selectively (cf. discussion in Section 3.4.1). Stereogenic alkylations of such enolates therefore may occur diastereoselectively. Especially important examples of such diastereoselective alkylations are shown in Figures 10.37 and 10.38. Figure 10.37 shows the alkylation of a chiral propionic acid ester—the ester is derived from an enantiomerically pure alcohol—via the E - and Z -cnolates. Figure 10.38 shows alkylations of two propi-... 

Only chiral propionic acid amides can be alkylated with still higher diastereoselectivity than chiral propionic acid esters. This is because according to Figure 10.15, the selectivity for the formation of a Z -configured amide enolate is higher than the se-... 

Two groups of chiral aromatic carboxylic acids are important commercial intermediates for the agricultural and pharmaceutical industries. The R enantiomer of a-phenoxypropionic adds confers biological activity for a number of herbiddes. The S enantiomer of a variety of arylpropionic adds is the biologically active form of the nonsteroidal antiinflammatory products labeled profens. Racemic mixtures of the alkyl esters of these propionic add derivatives have been effectiwly resolved to yield the desired optically active carboxylic acids (64-66). Figure 20 shows examples of the resolution of aromatic propionic acid esters. 

Figure 20 Lipase solution of (R,S)-arylpropionic acid and (R,S -oi-phenoxy-propionic acid esters.

The cyanomethyl-substituted pyrido[2,l-i ]quinazolinones 211 (R = CH2CN) can be transformed by chain elongation into the propionic acid and propionic acid ester derivatives. Reactions were effected by heating the cyanomethyl derivatives for 2 hr in diethyl carbonate in the presence of sodium hydride, followed by evaporation and treatment with methyl iodide and sodium hydride in dimethylformamide at 0°C, and finally by stirring of the evaporated oily residue in a mixture of isopropanol and coned, sodium hydroxide to obtain the acids,and in 0.5 N aqueous acetic acid to obtain the esters. ... 

Stereoselective synthesis of an a-alkylated ester has been carried out employing a polymer supported chiral oxazoline [13, 38]. An oxazoline bound ethyl moiety was alkylated with benzyl chloride to provide, after acid catalyzed detachment from the resin, an a-alkylated propionic acid ester in 43—48% yield and 56% ee. 

There are many examples of reaction (a) e.g., arenediazonium chlorides add to acrylic and methacrylic acids esters, and nitriles giving / -aryl-chloro-propionic acids, esters, and nitriles 242-244 and <%,/ -unsaturated aldehydes afford 3-aryl-2-chloropropionaldehyde and the analogous 2-bromo aldehydes.245,246 Butadiene undergoes 1,4-addition.247-249 Phenylacetylene and a benzenediazonium chloride solution that has been neutralized with sodium carbonate solution gives, at 25-30°, a 46.5% yield of <%-chlorostilbene.250... 

The natural steroids used for anabolic purposes in farm animals are estradiol-17 3 or its benzoic and propionic acid esters, progesterone, and testosterone. 

Definition Propionic acid ester of an ether of a propylene glycol, PEG deriv. of cetyl alcohol Empirical C28H56O6 Formula ... 

How many stereoisomers are possible for the propionic acid ester of 3,7,11-trimethyl-2-tridecanol ... 

Of particular note, A[,A[-dimethylbenzylamines 5.4 are the most popular with 350 articles reported, followed by such other popular compounds as benzyl methyl derivatives 5.30 with 168,2-phenhylpyridines 5.14 with 135, dimethylantinopropyl (or propenyl) compounds 5.22 with 159, alkyl (or aryl) ethyl (or ethenyl) ketones 5.19 with 108, diallyl (or diaryl or propenyl) phosphines 5.25 with 206, and alkyl (or aryl) propionic acid esters 526 with 164. 

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