Dihydrocinnamic acid derivatives

A third approach to asymmetric synthesis involving oxidative dimerisation of dihydrocinnamic acid derivatives is shown in scheme 13 ( f. scheme 7) [64,65]. By choosing an appropriate chiral auxiliary, either (-)- or (+)-hinokinin, for example, can be prepared. In either case removal of the chiral auxiliary leads to an anhydride having C2 symmetry which can be reduced to the lactone. 

OH group may be assumed to form the anion/molecule complex 139 which, however, is non-reactive with respect to further tautomerization. Rather, this complex loses the entire carboxylate residue as the fragment ion m/z 255), leaving the phenolic unit as a quinoid neutral fragment (Scheme 37) °. In a further work, 3,4-dihydroxybenzyl carboxylates derived from stearic acid (cf. 140), dihydrocinnamic acid and phenylacetic acid were studied under NC1(NH3)-MS/MS conditions. In these cases, deprotonation was found to take place exclusively at the phenolic sites, owing to the increased acidity of hydroxyl groups in a catechol nucleus, in contrast to simple phenols. Heterolysis of the benzylic C—O bond, e.g. in ions [140 — gives rise to reactive anion/molecule complexes,... 

Polymeric Evans auxiliary 76 was also applied to aldol reactions2 4 (Scheme 1.6.37). In a model reaction, immobilised dihydrocinnamic acid was converted into the boron enolate and reacted with isovaleraldehyde. Products were released by treatment of the resin with NaOMe. The p-hydroxy ester 79 was obtained in a 20 1 diasteromeric ratio, along with some ester 80 derived from unreacted starting material. 

A number of phenylpropanoid-derived compounds are capable of inhibition of seed germination and seedling growth of other plants. Dihydrocinnamic acid (79), from Ceratiola ericoides (Empetraceae), a common plant in the Florida scrub, was shown to inhibit both germination and growth of Schizachyrium scoparium (little blue stem, Poaceae), Leptochloa dubia (Poaceae), Rudbeckia hirta (As-... 

In plants and animals dihydrocinnamic acids (D 22.2.1) are the most important precursors of benzoic acids (for the formation of benzoic acid derivatives from shikimic acid cf. D 8 and D 8.2). The dihydrocinnamic acids are cleaved with the formation of a two carbon fragment and an aromatic aldehyde, which may be... 

A new diphosphine ligand, Norphos , catalyses the reduction of Z-a-(acetyl-amino)cinnamic acids to the expected dihydrocinnamic acids with optical yields of ca. 96%. ° The ligand is prepared from trans-vinylidenebis(diphenylphosphine oxide) by a Diels-Alder reaction with cyclopentadiene, classical resolution using (L)-(-)-dibenzoyltartaric acid, and finally reduction. The same substrates can also be reduced in ca. 80% optical yields using diphosphine ligands derived from enantiomerically pure menthoP or mandelic acid. ... 

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