Cinnamic acid/esters

Phenyl-propyl alcohol, CgH. CHj. CH.2. CHj. OH, is the next highest homologue of phenyl-ethyl alcohol, and is also known as hydro-cinnamyl alcohol. Like the last described bodies it has been known for many years, its first preparation being described in the Aivnalen (188, 202). It occurs as a cinnamic acid ester in storax, and as an acetic ester in cassia oil. It is prepared synthetically by the reduction of cinnamyl alcohol with sodium amalgam and water, or by the reduction of cinnamic or benzyl acetic esters with sodium and absolute alcohol. It has the following characters —... 

Benzyl Ginnamate.—The cinnamic acid ester of benzyl alcohol is a natural constituent of storax, tolu, and Peru balsams. It is a crystalline Bubstance with a characteristic sweet balsamic odour. It may be prepared by heating sodium cinnamate, alcohol, and benzyl chloride together under a reflux condenser. It is a useful ester where a sweet balsamic odour is required to be introduced into a perfume, especially cf the heavy type. It forms white, glistening prisms, which melt at 39°, and.decompose when heated to 350°. The best commercial specimens have the following characters —... 

Cinnamic acid esters can be converted to dienals via Grignard addition and Vilsmeier reaction (equation 184)306. 

The suitability of the polymer-Hnker conjugate was examined for a variety of transformations, in particular Pd°-catalyzed reactions. For instance, the polymer-bound aryl iodide (63) was transformed quantitatively in a Heck reaction to a cinnamic acid ester (64) and to biphenyl (66) in a Suzuki reaction. It gave an alkyne (65) in a Sonogashira reaction (Scheme 10.12). 

A study of the regioselectivity of the 1,3-dipolar cycloaddition of aliphatic nitrile oxides with cinnamic acid esters has been published. AMI MO studies on the gas-phase 1,3-dipolar cycloaddition of 1,2,4-triazepine and formonitrile oxide show that the mechanism leading to the most stable adduct is concerted. An ab initio study of the regiochemistry of 1,3-dipolar cycloadditions of diazomethane and formonitrile oxide with ethene, propene, and methyl vinyl ether has been presented. The 1,3-dipolar cycloaddition of mesitonitrile oxide with 4,7-phenanthroline yields both mono-and bis-adducts. Alkynyl(phenyl)iodonium triflates undergo 2 - - 3-cycloaddition with ethyl diazoacetate, Ai-f-butyl-a-phenyl nitrone and f-butyl nitrile oxide to produce substituted pyrroles, dihydroisoxazoles, and isoxazoles respectively." 2/3-Vinyl-franwoctahydro-l,3-benzoxazine (43) undergoes 1,3-dipolar cycloaddition with nitrile oxides with high diastereoselectivity (90% de) (Scheme IS)." " ... 

Phenylpropanoids are widespread in higher plants, especially in the plants that produce essential oils, e.g. plants of the families, Apiaceae, Lamiaceae, Lauraceae, Myrtaceae and Rutaceae. For example, Tolu balsam (Myroxylon balsamum, family Fabaceae) yields a high concentration of cinnamic acid esters, cinnamon (Cinnamomum verum, family Lauraceae) produces cinnamaldehyde, fennel (Foeniculum vulgare, family Apiaceae) is a good... 

Table III Photostationary State upon Irradiation of Stilbene and Cinnamic Acid Esters in Organic Solvents and in Cyclodextrins.

An example of the working curve approach, resulting from a study of the stereochemistry of the electrohydrodimerisation of cinnamic acid esters [38], is shown in Fig. 6.16. 

L. M. Minsk, W. P. Van Deusen, E. M. Robertson, Printing-Plate Resists of Cinnamic Acid Esters of Polyvinyl Alcohol and Cellulose, US Patent 2, 610, 120, 1952. 

Phenylpropynoic acid (13) can be prepared from cinnamic acid esters by the addition of bromine to the double bond followed by dehy-drobromination with alcoholic potassium hydroxide (Scheme 5.14). 

This procedure illustrates a general method for the preparation of phenylcyclopropanes from cinnamic acids, esters, aldehydes, or alcohols. It complements the Simmons-Smith reaction as a general method for the preparation of such cyclopropanes. It offers advantages over the Simmons-Smith method in cases in... 

Rice bran 4.2-5.2 y-oryzanol (cinnamic acid esters of sterols)... 

There is some evidence that y-oryzanol present in rice bran oil lowers semm total- and LDL cholesterol as well (16, 185, 188). Butter from the Shea tree, Butyro-spermum parkii, contains a very high level of 4,4-dimethylsterols (about 8%) mostly as esters of cinnamic acid (oryzanols). Apparent absorption of these sterols, as estimated by their disappearance from feces, was found to be 27-52% in Wistar rat and 13-49% in humans (189). It was found that the cinnamic acid esters of the 4-desmethylsterols of rice bran oils, but not those of the 4,4 -dimethylsterols of shea nut oil possess hypolipidemic activity (190). 

Homologues.—The homologues of benzyl alcohol result from substitution of the hydroxyl group in one of the methyl groups of xylene, mesitylene, etc., or, as in the examples previously given of secondary and tertiary aromatic alcohols, by the substitution of hydroxyl in a poly-carbon side chain either saturated or unsaturated. These need not be discussed further except to mention that both phenyl propanol, CeHs—CH2—CH2—CH2OH, and phenyl propenol, CeHs—CH = CH— CH2OH, are also found as cinnamic acid esters in storax. 

Illustrations of the application of LSV for studies of reactions under purely kinetic conditions include the oxidation of 9-substituted fluorenide ions [99] and the reduction of 2,6-diphenylpyrylium ions [100], in both cases leading to the neutral radical, which dimerizes in an RR-type reaction, the oxidation of 1,4-dithiafulvenes into tetrathiafulva-lenes [101], the oxidative ring opening of arylcyclopropanes [102], the reduction of fluoro-alkoxyarenes in liquid ammonia [103], and the competition between protonation and dimerization during the reduction of cinnamic acid esters in MeOH [104]. 

Electrolyses of substrates of the cinnamic acid ester family (Table 4) in anhydrous MeCN were shown to result in formation of 7-60% of the CHD [Eq. (3)], corresponding exclusively to the ( ) coupling as determined from the stereochemistry of the cyclopenta-none formed by hydrolytic decarboxylation [61]. The stereochemistry was later verified by x-ray crystallography [65]. The stereoselectivity in the coupling step was originally rationalized in terms of orientation of the substrate molecules at the electrode surface [61]. However, later kinetic studies have shown that dimerization of the radical anions is fairly slow (Table 3), and takes place in the diffusion layer at a distance from the electrode. 

Higher yields of the CHD were obtained in another series of the cinnamic acid esters (Table 4) upon reduction in DMF [68,69], and similar yields were obtained from substances with a Me, Et or Ph substituent at the )6-carbon in 12 [68]. 

For a series of cinnamic acid esters formed from chiral alcohols, reduction in DMF gave the CHD with from 0% de for the (—)-menthyl ester up to >95% de for the (—)-endo-hoxny ester [66] (Table 4). The menthyl and the bornyl cinnamates have virtually... 

Under identical experimental conditions (DMF, 0.28 M H2O, 0.1 M Et4NBr), a thorough study of a large series of cinnamic acid esters led to the conclusion that the EHD reaction followed the RR mechanism with rate-determining dimerization [16]. The rate constants for dimerization were shown to correlate closely with the eP values for the reduction process the more easily the substrate is reduced, the faster is the dimerization (Table 3) [16]. The phenomenon can for this closely related series of compounds be rationalized in terms of a systemic change of the unpaired electron density at the position of dimerization [76]. 

Baizer and coworkers established the most brilliant industrial electroorganic synthesis of the hydrodimerization of acrylonitrile to adiponitrile. They extended this hydrodimerization to a variety of activated olefins and in some cases [41 3] paid attention to the stereochemistry of products. However, their stereochemical data were not enough to discuss the stereochemical course of the reaction. Afterward, an attempt was made to provide a working hypothesis in the hydrodimerization of cinnamates by considering an orientated adsorption of radical anion intermediates on a cathode surface, but this was not persuasive because of a lack of experimental data on the stereochemistry of both the starting olefins and products. Recently Utley and coworkers [44-46] have reported stereochemical data of hydrodimers derived from a variety of cinnamic acid esters with chiral alcohol components. 

Glycosides of this vitamin (sometimes denoted as vitamin B3) were not described, however, there exists an evidence that bound niacin from wheat bran (termed niac)4in) has a single nicotinic acid moiety at least partially linked to an aromatic amine with glucose, xylose, and arabinose in a 6 3 1 molar ratio per molecule, with approximately three cinnamic acid esters [152,177,178]. It seems that these glycosidic complexes limit the bioavailability of the nicotinamide and for its liberation they must be treated, e. g., by soaking com in a lime solution, traditionally performed in Central America during production of tortillas [179]. 

Winterstein esters easily undergo P-elimination to A -cinnamic acid esters (Scheme I). It is not dear to what extent this conversion is enzymatic or only chemical. The conversion can take place on storage [31] or in mild acidic medium. Prolonged times (months) are required with silica gel [32], With compounds of the taxine B-type, the reaction can take place fairly easily on plant storage, though the extent of this reaction in the seeds is much less [30], The degradation of Winterstein esters of the taxine B-type (2a-d) has a dramatic effect on the composition of taxine, since Winterstein esters of the 2 -deacetoxyaustrospicatine-type (40 and... 

Main components During fermentation, vanillin (up to app. 2.5%) is formed from the odourless glucovanillin by enzymatic hydrolysis. Its aroma is rounded-off and modified by p-hydroxybenzoic acid, p-hydroxybenzaldehyde, p-hydroxybenzyl methyl ether, vanillyl alcohol, vanillic acid, cinnamic acid ester and various other trace constituents [291, 292], Also the resins, gums, amino acids and other organic acids contribute to the typical flavour of the cured beans [293[. For further constituents and characterisations of fruits from different growing areas see [294[. 

I.2.5. Phenylcyclopropanes by Metal Hydride Reduction of Cinnamic Acids, Esters,... 

Some coumarins possess anticoagulant properties (warfarin is a widely used example) and other derivatives are used as fluorescent brightening agents. A number of laser dyes are based on coumarin. Cinnamic acid esters are commonly used in sun-tan lotions to absorb UV light,... 

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