Cinnamic acids configuration

Cinnamic acid exists in two different configurations, as cis and trans isomerides. Ordinary cinnamic acid has the trans-ioim (fumaric... 

As the insertion of the carbon monoxide retains the configuration of the Pd-C bond, a modification of the procedure permits the conversion of /ra/w-cinnamic acid into the cis-isomer (Scheme 8.11) [5]. 

A great number of olefinic compounds are known to photodimerize in the crystalline state (1,2). Formation of a-truxillic and / -truxinic acids from two types of cinnamic acid crystals was interpreted by Bernstein and Quimby in 1943 to be a crystal lattice controlled reaction (5). In 1964 their hypothesis on cinnamic acid crystals was visualized by Schmidt and co-workers, who correlated the crystal structure of several olefin derivatives with photoreactivity and configuration of the products (4). In these olefinic crystals the potentially reactive double bonds are oriented in parallel to each other and are separated by approximately 4 A, favorable for [2+2] cycloaddition with minimal atomic and molecular motion. In general, the environment of olefinic double bonds in these crystals conforms to one of three principal types (a) the -type crystal, in which the double bonds of neighboring molecules make contact at a distance of -3.7 A across a center of symmetry to give a centrosymmetric dimer (1-dimer) (b) the / -type crystal, characterized by a lattice having one axial length of... 

The effect of polar groups on the diimide reaction is sensitive to the configuration of the attached groups. For example, fumaric acid (trans) is ten times as reactive as maleic acid (els ) and the ratio of reactivities of the geometrical isomers of cinnamic acid, trans/cis. is 10 3 (ref. 21b). In comparison, cis- and trans-2-butene have almost identical reactivities. The difference may be explained by a change in the degree of advancement of the transition state towards the saturated product where the eclipsed conformation would result in a greater non-bonded repulsive interaction between the cis-substituents than the trans. 

Arenediazonium o-benzenesulfonamide 89 was found to be a new and efficient reagent for the Heck-type arylation reactions of some common substrates containing C-C multiple bonds, i.e., ethyl acrylate, acrylic acid, acroleine, styrene, and cyclopentene <2006T3146>. The reactions are carried out in the presence of Pd(OAc)2 and afford arylated products, for example ethyl cinnamates, cinnamic acids, cinnamic aldehydes, and stilbenes, possessing an ( -configuration, and 1-arylcyclopentenes, in good to excellent yields (Equation 27). 

NMR spectroscopy is the most widely used method to investigate both the configuration and conformation of Knoevenagel products. The configuration of acrylic or cinnamic acids obtained by condensation of aldehydes with malonic acid and other 1,2-disubstituted alkenes can be determined from the value of the vicinal coupling constant Vh,h (between the protons of the double bond) on the basis of the relationship > Vh.h-hi. If only one isomer is available, the electronegativity of the substituents has... 

Chasmanthinine is the first diterpene alkaloid of this family that has been found to be esterified with cinnamic acid. Since chasmanthinine has been correlated with bikhaconine, whose absolute configuration is known, the absolute configuration of chasmanthinine is also known. 

Truxillic Acid. 2,4-Diphenyi-t,3-cyclobulanedi-carboxylic acid. C,(Hl(04 mol wt 296.3], C 72.96%, H 5.44%, O 21,60%. Cinnamic acid polymers obtained from the minor alkaloids of cocaine Liebermann, Ber. 21, 2342 (1888), Five stereoisomers have been obtained a-, y, t. peri- and eni-isomers. Stereochemical configurations Stoermer, Bacher, Ber. 57B, 15-23 (1924). 

As p-hydroxy-cinnamic acid can exist in either the or trans configuration, both were tested. The data (Table III) showed that the -isomer was more active than the trans-isomer. Saturation of the double bond in the aliphatic portion of the molecule was investigated by testing the dihydro-derivatives of p-hydroxycinnamic and 3,4-dihydroxycinnamic acids. The dihydro-acids were slightly more active than the corresponding cinnamic compounds. 

Cinnamic acids are phenylpropenic acids. The phenyl ring may be substituted by hydroxy and methoxy groups. The double bond of the side chain may have cis- or trans-configuration. c s- and trans-cinnamic acids are easily interconvertible. 

For example (one of many possible), hydroxylated cinnamic acids are ubiquitous in nature (largely in plants). Frequently, the hydroxyl groups are methylated. Investigations have shown that the process by which the methylation occurs here, as in many other cases, involves the transfer of the methyl group from SAM to the phenol. The process is shown to be, essentially, an Sn2 substitution by oxygen of the phenol on the methyl group of SAM with inversion of configuration at the methyl.The experiments were... 

Modification of the previously reported ligand (li ,2i )-bis(diphenyl-phosphinamino)cyclohexane (3,323) by N-methylation results in the preferential production of (S)-a-amino-acid derivatives from Z-a-(acylamino)cinnamic acids whereas the original ligand leads to the (i )-acids. Such inversions of product configuration have also been observed when the hydrogen pressure is... 

Hydroxycinnamic acids (HCAs) are a major class of phenolic compounds found in nature. They are secondary metabolites derived from tyrosine and phenylalanine, which have a C6-C3 carbon skeleton with a double bond in the side chain that may have a trans or cis configuration (Figure 3.11) [55]. Among the most common and well known HCAs are cinnamic acid, caffeic acid, ferulic acid, m-coumaric acid, o-coumaric acid, p-coumaric acid, and sinapic acid. 

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