Cinnamic adds

Two of the main raw materials used for bioconversion to L-phenylalanine are frous-cinnamic acid and acetamido cinnamic add (reactions 1 and 2 in Figure 8.6.)... 

Reaction 1 is governed by the enzyme phenylalanine ammonia lyase. This enzyme normally conducts the breakdown of L-phenylalanine to from-cinnamic add and ammonia. However, die reaction can be reversed leading to the production of L-phenylalanine from frans-dnnamic add by using excess ammonia. 

L-Phenylalanine can be synthesised from trims-cinnamic add (Figure A8.12) catalysed by a L-phenylalanine ammonia-lyase from Rhodococcus glutinis. The commercialisation of the process was limited by the low conversion (70%), low stability of the biocatalyst and die severe inhibition exerted by trims-cinnamic add. These problems were largely overcome by researchers at Genex. The process, commercialised for a short period by Gen ex, involves a cell-free preparation of phenylalanine-ammonia-lyase activity from Rhodotorula rubra. 

Morus alba callus and cell suspension cultures specifically produce chalomoradn 5 and kuwanon J 6 from dnnamoylpolyketide intermediates. Administration of [2- C]cinnamic add AT-acetylcysteamine thioester to the M. alba cell cultures revealed the cinnamoyl CoA intermediate to be a significant precursor <99H(50)989>. For further biosynthetic investip-tions see <99H(51)231>. 

Table 4. Structure of the most common cinnamic adds...

Figure 28. Topochemical rules are based on the photochemical behavior of cinnamic adds in three crystallographic modifications.

NMR spectroscopy has been used to study the species formed in solution by interaction of cinnamic add derivatives with asymmetric hydrogenation catalysts.257,258 Such studies are necessarily limited to those spedes which accumulate in adequate concentration and have sufficiently long lifetimes for observation by NMR. In catalytic reactions as rapid as those described here, such complexes appear likely to be outside rather than in the operating catalytic cycle.91... 

Figure 5. Mean length of fully expanded third and fourth internodes of Meteor pea treated with 0.1 fig. of gibberellin and 0.1 and lfig. of p-coumaric acid and cinnamic add and 1 and 10 fig. of fi-hydroxy-...

Wall, V.M., Eisenstadt, A., Ager, D.J. and Laneman, S.A. (1999) The Heck reaction and cinnamic add synthesis by heterogeneous catalysis palladium on carbon catalyst gives improved production. Platinum Met. Rev., 43, 138. 

This question is about three related acid-catalysed reactions (a) the isomerization of Z-cinnamic adds to -cinnamic acids (b) the dehydration of the related hydroxy-acids (c) the racemization of the same hydroxy-acids. You should be able to use the information provided to build up a complete picture of the interaction of the various compounds and the intermediates in the reactions. 

Hydrocirinamic acid has been prepared by the reduction of cinnamic add with sodium amalgam,1 with hydriodic acid at ioo°,2 and with phosphorus and hydriodic acid 3 by the action of potassium cyanide on /3-phenylethyl chloride followed by hydrolysis 4 by the add hydrolysis of benzyl-acetoacetic ester 5 and by several other methods of no preparative value. It has also been prepared electrolytically by the reduction of cinnamic add in alkaline solution on cathodes of lead 8 and mercury.9... 

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