Cinnamic acid ortho

Benzaldehyde, ortho-Nitro Cinnamic Acid, ortho-Nitro Phenyl Propiolic Acid.—Later he started with benzaldehyde and obtained first benzal chloride which by condensation with sodium acetate yielded cinnamic acid salt. 

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. 

Phenyl aryl cyclopropenones16 were cleaved by methanolic KOH to a mixture of cis aryl cinnamic acids (318/319 R = phenyl, R = aryl), whose rates of formation gave rise to a linear Hammett-type correlation with a values in the range of -0.268 to +0.373 and p = 0.75. This also indicates that cleavage yielding the more stable carbanion is preferred. Interestingly, ortho-substituted aryl phenyl cyclopropenones gave only a-phenyl-0-aryl acrylic acids (319 R = phenyl, R = aryl), which was explained in terms of steric interactions. 

Neither the anilide of cinnamic acid94 nor the diphenyl substituted acroyl anilide 138 95 yields any product of rearrangement or cyclodimerization. Upon irradiation of 138 in benzene solution in a Pyrex reactor, only the isomeric /9-lactams 139 (2.3%) and 140 (37%), in addition to dihydrocarbostyril 141 (5%), were isolated. The latter is the major product upon irradiation of alkyl substituted acroyl anilides.96 On the other hand, the closely related phenyl cinnamate rearranges regularly to the ortho- and para-positions97 and does not dimerize as the other alkyl esters of cinnamic acid.98... 

The 13C chemical shifts of the parent compound were assigned by comparison with the spectrum of cinnamic acid (see Section 4.11.2) and from the knowledge that for benzenoid methine carbons introduction of an acyloxy function into the benzene ring causes small shifts of the meta carbons, and shifts the signals of the para carbons to higher field, while the ortho carbons become even more shielded (Fig. 5.16) [635]. 

Coumaric Acid, Coumarinic Acid or Hydroxy-cinnamic Acid [called Cumarsaure, Cumarinsaure, (Oxyphenyl)-acrylsaure or Oxy-zimtsaure in Ger], CgH803 mw 164-15, O 29-24%. This compd exists as ortho-, meta - para - derivs. The ortho deriv is known in both trans cis forms ... 

The simple coumarin nucleus (Fig 7.3), which is derived by lactone formation of an ortho-hydroxy-czs cinnamic acid, is a common metabolite in higher plants and is often found in glycosidic form. Coumarins are common in Api-aceae, in certain genera of Fabaceae (e.g. Dipteryx odorata, Melilotus officinalis), Poaceae (e.g. Anthoxanthum odoratum) and Rubiaceae (e.g. Galium odoratum). However, proliferation of coumarins to the status of major chemical markers occurs in only a few cases, most notably, but not exclusively, in the Api-aceae (subfamily Apioideae) and in the Rutaceae (Gray and Waterman, 1978 Murray et al., 1982). In these cases, the coumarin nucleus has almost invariably been embellished by the addition of a prenyl unit leading to furocoumarin (Fig 7.3) and pyranocoumarin structures. 

A cinnamic acid group directs a substituent to enter the ortho position and hence the benzaldehyde should be nitrated first and then the cinnamic acid group synthesized ... 

From ortho-Amino alpha-Phenyl Cinnamic Acid.—Referring to cinnamic acid (p. 697) the constitution of ortho-amino alpha-phenyl cinnamic acid will be as shown by the following relationships. 

Baeyer and Emmerling, Indole from ortho-Nitro Cinnamic Acid.—... 

The first relationship between members of the indole group and simpler benzene derivatives was that established by Baeyer and Emmerling, 1869, in synthesizing indole from ortho-mtro cinnamic acid by fusion with potassium hydroxide and iron filings. The steps in the synthesis are probably as follows ... 

From the cinnamic acid salt by nitration he obtained ortho-nitro cinnamic acid. This yielded a di-bromide which by loss of two molecules of hydrogen bromide was converted into ortho-nitro phenyl propiolic acid (p. 700). 

It is interesting that when the functional groups are not directly attached to the aromatic ring, orientation cannot be predicted from a consideration of the point of highest electron density. Cinnamic acid (XII),7 w-nitrostyrene (XIII),8 and 2-phenylethenesulfonyl chloride (XIV),9 all orient predominantly ortho-para, although we should expect these positions to be electronically deficient. 

While prevention of substitution or cyclisation reaction at an electrophilically more reactive site is one of the techniques to promote reaction at the less reactive site, strategies to specifically direct substitution at the less reactive position are also known. Phenol, for example, is specifically formylated at ortho position in alkaline medium Cinnamic acid is specifically nitrated at ortho position by N Oj. It is possible that in such reactions, the first step is the complexation of the reagent with the substituent already present, which then favours the attack of the reagent at the sterically close (to the complexing group) aromatic position which is ortho to the substituent already present. 

Further steps in the synthesis of coumarin via the ortho-hydroxy benzaldehydes involve a Perkin reaction. Here, in the first instance, a cinnamic acid is obtained. The cinnamic acids are obtained more conveniently by the Wittig reaction of the aldehydes with the stable phosphoranes, Ph3P=C—COOEt. Indeed lithiation... 

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