Cinnamaldehyde, structure

FIGURE 11.16 Reaction mechanism for oxidation of a cinnamaldehyde structure with alkaline hydrogen peroxide. 

Dehydrochlorination of dichloroacetyl chloride by triethylamine in the presence of a Schiffs base with a cinnamaldehyde structure through... 

Quinone methides play an important role in lignification. They are produced directly, as intermediates, when lignin monomers, be they hydroxycinnamyl alcohols, hydroxy-cinnamaldehydes, or hydroxycinnamates, couple or cross-couple at their 8- positions. A variety of postcoupling quinone methide rearomatization reactions leads to an array of structures in the complex lignin polymer (Fig. 12.2). 

In general, the results point to the edges and/or corners (small particles) favoring hydrogenation of the C=C bond whereas the planes (large particles) favor hydrogenation of the C=0 bond. This seems to be true for all compounds on Pt (see Table 2.6, lines 10-27, and 29-30) and for cinnamaldehyde on Ru and Rh (see Table 2.6, lines 33, 34, 37, and 38) however, citral on Ru did not exhibit this effect (see Table 2.6, lines 35 and 36), according to the authors statement. The reasons for this latter result are not clear. Why, for example should other alkyl-substituted a,P-unsaturated aldehydes exhibit this structure sensitivity and citral not Clearly, other factors are also at play. 

A more general reaction between kojic acid and aldehydes is a trimolecu-lar condensation discovered by Barham and Reed." By a process of elimination, they arrived at the conclusion that C6 of kojic acid was most probably the point of attack two molecules of kojic acid reacted with one molecule of the aldehyde, with the elimination of one molecule of water, giving a product of structure LXXV. Such compounds were prepared from kojic acid and the following aldehydes the normal alkanals from formaldehyde to heptanal, benzaldehyde, cinnamaldehyde, hydrocinnamaldehyde, 2-furaldehyde, and acrolein. The compound derived from kojic acid and benzaldehyde (LXXV, R = phenyl) was also obtained by treating LXXII (R = phenyl) with hot, aqueous sodium carbonate.92... 

Dehydrodarlingianine (69) and dehydrodarlinine (72) were synthetized by base-catalyzed reaction of hygrine with cinnamaldehyde and benzaldehyde, respectively. The relative stereochemistry of darlingianine (65) was established by X-ray diffraction (111). The structure of the other bases was established by chemical correlations as well as by spectroscopic methods. The absolute configurations of these bases remain to be determined. 

Platts and Tomkinson reported a detailed quantitative study of the iminium ion catalysed Diels-Alder reaction between cyclopentadiene and cinnamaldehyde catalysed by trifluoromethyl pyrrolidine salt 182-HPFg [227]. This combination of secondary amine, co-acid and dienophile allowed the isolation and structural elucidation of the reactive iminium ion intermediate. As a result it was possible to... 

Oxovanadium(IV) complexes have also been prepared with the carbohydrazones and thiocarbohydrazones formed in the condensation of carbohydrazide or thiocarbohydrazide with benzaldehyde, o-nitrobenzaldehyde, anisaldehyde, cinnamaldehyde, acetophenone and 2-acetylpyridine.845 file values are 1.68-1.72 BM and v(V=0) is at 960-980 cm-1. The compounds, [V0(L)2(H20)j (147), were suggested to be of structure (12) (p. 487).845... 

When the groups on either end of a double bond are the same or are structurally similar to each other, it is a simple matter to describe the configuration of the double bond as cis or trans. Oleic acid, for example, a compound that can be obtained from olive oil, has a cis double bond. Cinnamaldehyde, responsible for the characteristic odor of cinnamon, has a trans double bond. 

The structure of the reactive ternary complex composed of the enzyme NAD+, and 4-bromobenzyl alcohol was solved at 2.9-A resolution.14 This was possible because there is a favorable equilibrium between this complex and the enzyme-bound ternary complex reaction product of NADH and 4-bromo-benzaldehyde. The structure of the unreactive product-like complex composed of the enzyme, the coenzyme analogue H2NADH (i.e., NAD+ in which the nicotinamide ring has been reduced to 1,4,5,6-tetrahydronicotinamide), and trans-4- (N, A-dimethylamino)-cinnamaldehyde (DACA) was also solved at the same resolution.18... 

With benzaldehyde 144 or halogenated derivatives (Cl, F) as acceptors the yeast-PDC-catalyzed addition proceeds with almost complete stereoselectivity to furnish the corresponding (R)-configurated 1-hydroxy-1-phenylpropanones 145 [447]. For practical reasons, whole yeast cells are most often used as the catalyst, with only small loss of enantioselectivity [423,424]. The conversion of benzaldehyde in particular has gained industrial importance because the acyloin is an important precursor for the synthesis of L-(-)-ephedrine [448]. Otherwise, the substrate tolerance is remarkably broad for aromatic aldehydes on the laboratory scale, however, yields of acyloins are usually low because of the prior or consequent reductive metabolism of aldehyde substrate and product, giving rise to considerable quantities of alcohol 146 and vicinol diols 147, respectively [423,424,449], The range of structural variability covers both higher a-oxo-acids (e.g. -butyrate, -valerate) as the donor component, as well as a,/J-un-saturated aldehydes (e.g. cinnamaldehyde 148) as the acceptor [450]. 

Figure 4. Structure of some cinnamaldehyde whose spectra...

The chief constituents of leaf oil of cinnamon cassia from Yunnan province were cinnamaldehyde (64.1-68.3%), ( )-2-methoxy cinnamaldehyde (8.4-10.5%) and ( )-cinnamyl acetate (4.5-12.5%) (Li etal., 1998). The structures of the chief volatile components of cinnamon oil are shown in Fig. 7.1. 

At present there is no single procedure available for the determination of ethylenic groups in lignin which can be applied reliably to any type of sample without regard for the particular structural environment in which these units exist. Hence, most of the more widely accepted methods essentially consist of procedures used for the determination of larger structural elements comprising lignin, for example, cinnamaldehyde, cinnamyl alcohol, and stilbene units, in which the carbon-carbon double bond is incorporated. 

In another method based on the elimination of ring-conjugated ethylenic groups, the combined cinnamaldehyde and cinnamyl alcohol content of lignin in wood has been estimated through conversion of these structures to tetrahydrofuran derivatives by hydroformylation in the so-called oxo-reaction (Nahum 1969). In this particular analysis, the results apply only to the monomer fraction released during the hydroformylation reaction. 

Diastereoselective addition in Et20/HMPT (1 1) leads to the (5)-aldehyde with an enantiomeric excess of 40%, whereas in -hexane the (2 )-aldehyde is formed with 80% ( ) enantiomeric excess. The (2 )-configured aldehyde is also obtained in benzene and in dichloromethane, but with lower ee values of 50% and 25%, respectively. Inverse results were obtained with a chiral oxazolidine prepared from ( )-cinnamaldehyde and (+)-ephedrine. Here, the (5)-aldehyde with ee = 79% is formed in -hexane, and the (7 )-aldehyde in Et20/HMPT (1 1) with ee = 50% [703], This result may be due to different structures of the organocopper reagent, and hence of the diastereomorphic activated complexes, in nonpolar solvents ( -hexane, benzene, dichloromethane) and in EPD solvents (Et20/HMPT) [703]. 

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