Cinnamic acid derivatives, acylation

Klumpp and co-workers362 have performed a detailed study of the acylation reactions of benzene with a variety of cinnamic acid derivatives in triflic acid. Cinnamic acids with alkyl or weakly electron-withdrawing groups (F, Br) on the phenyl ring give the corresponding substituted indanones as a result of a two-step... 

Flavone glycosides often occur as acylated derivatives either with aliphatic or aromatic acids. Hydroxy-cinnamic acid derivatives are the most frequent in nature and MS fragmentations of these types of compounds show ions produced by the loss of 146,162,176, or 206 m.u., corresponding to the losses of the acyl residues />-coumaroyl, caffeoyl, femloyl, or sinapoyl, respectively. Brassicaceae species are rich in flavonoid glycosides acylated with hydroxyl-cinnamic derivatives, and most of them... 

In the laboratory of D. Ma, the asymmetric synthesis of several metabotropic glutamate receptor antagonists derived from a-alkylated phenylglycines was undertaken. The preparation of (S)-1-aminoindan-1,5-dicarboxylic acid (AIDA) started with the Perkin reaction of 3-bromobenzaldehyde and malonic acid. The resulting ( )-cinnamic acid derivative was hydrogenated and the following intramolecular Friedel-Crafts acylation afforded the corresponding indanone, which was then converted to (S)-AIDA. 

The reaction of crotonic and cinnamic acid derivatives with 296 was very dependent upon the nature of the carboxylate derivative used in the aza-annulation and the conditions of the reaction (eq. 61). When the corresponding acid chloride was used in the presence of pyridine, only A -acylation was observed to yield 303.85 However, when 296 was deprotonated with NaH and then treated with the ethyl ester of either crotonic or cinnamic acid, aza-annulation occurred to give 302. 

Glycine conjugation Glycine Acyl-CoA glycinetransferase (mitochondria) Acyl-CoA derivatives of carboxylic acids Salicylic acid, benzoic acid, nicotinic acid, cinnamic acid, cholic acid, deoxycholic acid... 

The Perkin synthesis of cinnamic acids is considered to involve reaction of the enolate anion derived from the acid anhydride with the aldehyde, giving rise to the alkoxide (391). Intramolecular acylation follows and the resulting /3-acyloxy derivative undergoes elimination to the unsaturated acid (Scheme 125). 

Stilbenoids are derived from cinnamic acid and three acetate units from mal-onyl coenzym A. The first part of the biosynthesis is in common to flavonoids. The two biosynthetic routes are diverging at the point of cyclization of a styryl-3,5,7-triketoheptanoic acid. A C-acylation produces a chalcone and subsequent modifications lead to the flavonoids. An aldol condensation of the same intermediate polyketide produces a stilbene-2-carboxylic acid that is unstable and constitutes a range of structures known as stilbenoids. Figure 9C.5 shows an overview of the biosynthetic pathway (Gorham 1995). 

A controlled MW irradiation (provided from modified MW oven) of a 1 1 mixture of diazo compound 436 and the simple acyl azides derived from benzoic and cinnamic acids results in the synthesis of oxazindiones 497a and 497b, respectively (Scheme 160) (20090L5706). 

The sugars and their derivatives have been esterified with many other organic acids. Among these are the fatty acids and cinnamic acid 107). Most of the products have been made by the action of acyl halides and pyridine on sugars. The fatty acid esters are similar in properties to the natural fats, the glycerol esters. 

Typical polyketides related to lignans and flavonoids are styrylpyrones derived from cinnamic acids (the corresponding acyl-CoAs). An example of styrylpyrones is (2R,T )-4-methoxy-2-(2 -phenyleth-l -en-T-yl)-2,3-dihydropyran-6-one, better known... 

Little work at the biochemical level has been carried out on the synthesis of phenolic esters. The enzymic transfer of glucose from UDPG to carboxylic acids has been demonstrated and it is possible that the 1-0-hydroxycinnamoyl esters of /3-D-glucose are formed by this means. Although there is little experimental evidence yet to confirm this supposition, other natural phenolic esters are believed to be derived by transfer of the acyl group from co-enzyme A precursors. The activation of cinnamic acid in the presence of co-enzyme A has thus been reported to occur with extracts of Beta... 

The oxidative cleavage of C=C double bonds is found in oxidative C-C bond-forming reactions. For example, when the indolizine 87 was reacted with cinnamic acid in the presence of a palladium catalyst under oxidative reaction conditions, the acylated indolizine 88 was generated as the major product (Scheme 7.34) [49]. The acyl group derives from the p-carbon (designated by a black circle) of the cinnamic acid. When the amine 89 reacted with -butyl acrylate under analogous reaction conditions, phenanthridine was produced in... 

According to the acyl-polymalonate hypothesis, chain-starter units other than acetate may be involved in the biosynthetic process (c/. Scheme 1). In this connection, the naturally occurring stilbenes and derivatives are produced by condensation of a cinnamate unit with three malonate units followed by aldol condensation of the enzyme-bound P-triketo-ester intermediate (77). " Secondary transformations (p. 183) may also occur at a pre-aromatic or postaromatic stage in the biosynthesis. Previous attempts to demonstrate the intermediacy of P-triketo-esters in the biosynthesis of stilbenes resulted in the reported conversion of cinnamoyltriacetic acid (77 R = H, as acid) into pinosylvin (79) by acetone powders prepared from leaves of a mutant of Eucalyptus sideroxylon. However, a subsequent report has indicated that this conversion cannot be repeated and this has prompted the explanation that P-polyketo-ester intermediates are bound to the enzyme and do not occur in the free state. Several difTerent preparations of acetone powder from E. 

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