Cinnamic addition

Cinnamic acid can be readily esterified by the Fischer-Speier method without any risk of the addition of hydrogen chloride at the double bond. Proceed precisely as for the preparation of ethyl benzoate (p. 104), using 20 g. of cinnamic acid and 20 ml. of rectified spirit. When the crude product is poured into water, a sharp separation of the ester is not readily obtained, and hence the addition of about 10 ml. of carbon tetrachloride is particularly desirable. Finally distil off the carbon... 

As a typical example, the catalytic reaction of iodobenzene with methyl acrylate to afford methyl cinnamate (18) is explained by the sequences illustrated for the oxidative addition, insertion, and /3-elimination reactions. 

The diazonium salts 145 are another source of arylpalladium com-plexes[114]. They are the most reactive source of arylpalladium species and the reaction can be carried out at room temperature. In addition, they can be used for alkene insertion in the absence of a phosphine ligand using Pd2(dba)3 as a catalyst. This reaction consists of the indirect substitution reaction of an aromatic nitro group with an alkene. The use of diazonium salts is more convenient and synthetically useful than the use of aryl halides, because many aryl halides are prepared from diazonium salts. Diazotization of the aniline derivative 146 in aqueous solution and subsequent insertion of acrylate catalyzed by Pd(OAc)2 by the addition of MeOH are carried out as a one-pot reaction, affording the cinnamate 147 in good yield[115]. The A-nitroso-jV-arylacetamide 148 is prepared from acetanilides and used as another precursor of arylpalladium intermediate. It is more reactive than aryl iodides and bromides and reacts with alkenes at 40 °C without addition of a phosphine ligandfl 16]. 

The cinnamate ester prepared as above (23.2 g. 79 mmol) was added as a solid slowly to refluxing xylene (500 ml) over a period of 3 h at a rate that prevented accumulation of unreacted azidocinnamate in the solution (monitored by gas evolution through a gas bubbler). The solution was refluxed for an additional 2 h after gas evolution ceased. The reaction mixture was cooled and the solvent removed in vacuo. The residue was recrystallized from methanol to give pure product (20.7 g, 99% yield). 

Physical and Chemical Properties. The (F)- and (Z)-isomers of cinnamaldehyde are both known. (F)-Cinnamaldehyde [14371-10-9] is generally produced commercially and its properties are given in Table 2. Cinnamaldehyde undergoes reactions that are typical of an a,P-unsaturated aromatic aldehyde. Slow oxidation to cinnamic acid is observed upon exposure to air. This process can be accelerated in the presence of transition-metal catalysts such as cobalt acetate (28). Under more vigorous conditions with either nitric or chromic acid, cleavage at the double bond occurs to afford benzoic acid. Epoxidation of cinnamaldehyde via a conjugate addition mechanism is observed upon treatment with a salt of /-butyl hydroperoxide (29). 

The addition of benzonitrile oxide to acrylic acid gave only the 4-carboxylic acid (441) (59MI41601), while addition to cis- and trans-cinnamic esters gave cis and trans diastereomeric pairs of 4-carboxylic acids (442) (Scheme 100) (59MI41600). Arbisono repeated the experiment and, when methyl c/s-cinnamate was used, in addition to the 4-carboxylic acid some 5-carboxylic acid (442) was isolated (66MI41600). The reaction of vinyl bromides with benzonitrile oxide yielded only an isoxazole and not a bromoisoxazoline (Scheme 101) (78JCR(S)192). 

The couplings of vicinal protons in 1,2-disubstituted alkenes lie in the range 6-12 Hz for cis protons (dihedral angle 0°) and 12-17 Hz for trans protons (dihedral angle 180°), thus also following the Karplus-Conroy equation. Typical examples are the alkene proton AB systems of coumarin (16a, cis) and tra 5-cinnamic acid (16b), and of the cis-trans isomers 17a and b of ethyl isopente-nyl ether, in addition to those in problems 3, 4, 8, 11, 13 and 38. 

The addition of diazomethane to unsaturated esters (1), as ethyl acrylate, methyl crotonate and ethyl cinnamate, was investigated by Auwers who showed that the primary addition product is a A -pyrazoline (2) which rearranges spontaneously to the conjugated A -pyrazoline (3). 

Cinnamic Acid.—The reaction, which takes place when an aldehyde (aliphatic or aromatic) acts on the sodium salt of an aliphatic acid in presence of the anhychide, is known as Perkin s reaction, and has a ery wide application. Accoid-ing to the result of Fittig s researches on the properties of the unsaturated acids described below, the reaction occurs in two steps. The aldeh) de forms first an additive compound with the acid, the aldehyde caibon attaching itself to the n-carbon ii.e.i nevt the carbovyl) of the acid. A saturated hydiOKy-acid is formed, which is stable, if the a-carbon is attached to only one atom of hydrogen, as in the case of isobutync acid,... 

In Corey and Chaykovsky s initial investigation, a cyclic ylide 79 was observed from the reaction of ethyl cinnamate with ylide 1 in addition to 32% of cyclopropane 53. In a similar fashion, an intermolecular cycloaddition between 2-acyl-3,3-bis(methylthio)acrylnitrile 80 and 1 furnished 1-methylthiabenzene 1-oxide 81. Similar cases are found in transformations of ynone 82 to 1-arylthiabenzene 1-oxide 83 and N-cyanoimidate 84 to adduct ylide 85, which was subsequently transformed to 1-methyl-lX -4-thiazin-l-oxide 86. ... 

The synthesis of isoxazolines usually takes the most thermodynamically favorable course to yield solely the more stable isomer. However, cinnamic acids (38) give not only isoxazoline-4-carboxylic acids (39) but also, as a by-product, the less stable isoxazoline-5-carboxylic acids (40)" which on heating undergo retro-addition. ... 

The use of ionic liquids as reaction media for the palladium-catalyzed Heck reaction was first described by Kaufmann et ak, in 1996 [85]. Treatment of bromoben-zene with butyl acrylate to provide butyl trans-cinnamate succeeded in high yield in molten tetraallcylammonium and tetraallcylphosphonium bromide salts, without addition of phosphine ligands (Scheme 5.2-16). 

Ester enolates which contain the chiral information in the acid moiety have been widely used in alkylations (see Section D.1.1.1,3.) as well as in additions to carbon-nitrogen double bonds (sec Section D.1.4.2.). Below are examples of the reaction of this type of enolate with aldehydes720. The (Z)-enolate generated from benzyl cinnamate (benzyl 3-phenylpropcnoate) and lithium (dimethylphenylsilyl)cuprate affords the /h/-carboxylic acid on addition to acetaldehyde and subsequent hydrogenolysis, The diastereoselectivity is 90 10. 

The conjugate addition of lithium cuprates to cinnamates 1 bearing a chiral oxazolidine or imidazolidine ring at the ortho position produced 2 in good to excellent yield upon hydrolysis14. 

As shown in Schemes 10-44 and 10-45, two products may be formed in a Meerwein reaction Scheme 10-44 shows a simple aryl-de-hydrogenation of cinnamic aldehyde, whereas Scheme 10-45 shows an aryl-de-hydrogenation combined with the addition of HC1 to the double bond of the methyl ester of cinnamic acid. No systematic studies have been made as to which of the two products will be formed in a given reaction, what experimental conditions will favor one or the other product, and what substituents or other structural characteristics of the alkene influence the ratio of the two types of product. The addition product can, in most cases, easily be converted... 

The ionization of benzoic acids in water at 25° was used by Hammett as the standard reaction for the original qp treatment (2a). This reaction and several analogous reactions, e.g., ionization and ester saponification rates of benzoic acids, cinnamic acids, and phenylpropiolic acids, gives ap correlations of relatively high precision. Taft and Lewis classified such reactions in an A category (2f). Reexamination of these A reactions, as well as additional analogous data which have become available subsequently, provided eight reaction series of data of apparently comparable reliability. In the para position, each of these sets of data meets the necessary condition of a minimal basis set... 

The trans cinnamic acid and phenyl propiolic acid data involve fits of essentially the same precision at o-, m-, and p- positions (SD =. 05 . 02). However, the RMS of these sets is quite low, and consequently, / values of. 200 prevail. The interpretation of these results is therefore uncertain. To the extent that the results of Table VII are meaningful, it is of particular interest that Kj =p°Ip =. 68 for the phenyl propiolic acid, whereas for the tram cinnamic acids, K° = 1.02. These results suggest that in contrast to the ortho substituted benzoic acids, the lines of field forces in the ortho substituted phenyl propiolic acids do (partly at least) penetrate regions of hi dielectric solvent. The results for the tram cinnamic acids would then indicate some (but not complete) exclusion of solvent resulting from the presence of the vinyl hydrogens. These interesting results from the application of eq. (1) clearly need to be confirmed by additional studies. 

Charrette and Lebel [24] developed a catalytic enantioselective cyclopropa-nation of trans-cinnamate esters with diazomethane. Their procedure involves an argon-flow-mediated diazomethane addition, leading to high yields (up to 80%) in products with up to 80% ee, by using the bis(oxazoHne) arising from phenylglycinol (Scheme 10). 

The combination of CsF with Si(OMe)4 58 is an efficient catalyst for Michael additions, e.g. of tetralone 130 to methacrylamide, followed hy cyclization of the addition product to the cyclic enamide 131 in 94% yield [67]. Likewise, addition of the lactone 132 to methyl cinnamate affords, after subsequent cyclization with tri-fluoroacetic acid, the lactam 133 in 58% yield [68] whereas < -valerolactam 134, with ethyl acrylate in the presence of Si(OEt)4 59/CsF, gives 135 in 98% yield [69]. Whereas 10mol% of CsF are often sufficient, equivalent amounts of Si(OEt)4 59 seem to be necessary for preparation of 135 [69] (Scheme 3.11). 

One of the distinguishing features of liverworts is their capacity to produce a variety of volatile, often very fragrant, oils that occur in oil bodies distributed over much of the surface of the organism. Several of these volatile compounds figure prominently in defining geographically different chemotypes in several countries. Toyota et al. (1997) examined 280 specimens of C. conicum collected at Kamikatsu-cho and Katsuura-cho, both Katsuura-gun, Tokushima. Three chemotypes were identified based upon their major components. Chemotype-I-accumulated (-)-sabinene [420], chemotype-II-accumulated (H-)-bomyl acetate [421], and chemotype III was characterized by methyl cinnamate [422] (see Pig. 5.4 for structures). In addition to a number of compounds known from previous studies of C. conicum, three... 

Stabilization of crude and purified anthocyanin extracts from agai by the addition of tannic acid resulted in a 65% half-life increase of anthocyanins from the crude extract and 610% of the half-life of the purified one. Although tannic acid was considered an efficient copigment,in general all cinnamic acids give unpleasant odors and tastes to solutions. 

The metabolism of cinnamate and w-phenylalkane carboxylates has been studied in Rhodopseudomonaspalustris (Elder et al. 1992), and for growth with the higher homologs additional CO2 was necessary. The key degradative reaction was ()-oxidation, for compounds with chain lengths of three, five, and seven carbon atoms, benzoate was formed and further metabolized, but for the even-numbered compounds with four, six, and eight carbon atoms phenylacetate was a terminal metabolite. 

The hydrogenation of a cinnamate was also investigated as a first step to determine kinetics and finally to come to a quantitative determination of kinetic models and parameters in asymmetric catalysis [64]. The enantiomeric excess of enantioselective catalytic hydrogenations is known to be dependent on pressure, chiral additives and mixing. Such dependences are often due to kinetics, demanding appropriate studies. 

Several additional benzoic and cinnamic acid derivatives were tested (28-31). 

Thermal degradation of Irganox 1076 in air was studied by means of HPLC-UV/VIS and by preparative HPLC-NMR. At 180 °C cinnamate and dimeric oxidation products are formed, and at 250 °C de-alkylation products are observed [660], On-line LC-NMR hardly covers a real need in polymer/additive analysis, as the off-line option is mostly perfectly adequate for that purpose. 

For PMMA/additive dissolutions, it was not possible to identify any additive characteristic mass peaks, either by direct laser desorption or with matrix-assistance (dithranol, DHBA or sinapinic acid, 4-hydroxy-3,5-dimethoxy-cinnamic acid). This has again been ascribed to very strong interaction between PMMA and additives, which suppresses desorption of additive molecules. Also, partial depolymerisation of pho-tolytically labile PMMA by laser irradiation may play a role, which leads to saturation of the detector by PMMA fragment-ions and disappearance of additive mass peaks below noise level. Meyer-Dulheuer [55] has also reported MALDI-TOFMS analysis of a coating/2-ethylhexyldiphenylphosphate sample. Quantitative determination of the additives by means of MALDI-ToFMS proved impossible. Possibly the development of reproducible (automated) sample handling procedures or thin films might overcome this problem. 

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