Methyl-frans-cinnamate

Several building blocks were prepared separately (Chart 7). Methyl frans-cinnamate gave by Sharpless enantiocontrolled dihydroxylation a diol from which by a series of stereo- and regioselective transformations (96) and Ru-catalyzed oxidation for transformation of the phenyl into a carboxyl group accompanied by adequate protection (97) and deprotection steps the protected OHAsp derivative 98 was obtained. 

Benzoic and salicylic acids. Two of the simplest plant acids arising from fraus-cinnamate are benzoic acid, accumulated in plums and cranberries, and salicylic acid, present in all green plants and accumulated as methyl esters or glycosides in some plants, e.g., those of the willow family. Salicylic acid is made by hydroxylation of benzoic acid,177 which can be formed from frans-cinnamate by P oxidation as depicted in Fig. 25-8, but it may also arise from isochoris-mate as shown in Fig. 25-2.178 Salicylic acid plays a central role in resistance of plants to a variety of... 

The addition of benzonitrile oxide to acrylic acid gave only the 4-carboxylic acid (441) (59MI41601), while addition to cis- and frans-cinnamic esters gave cis and trans diastereomeric pairs of 4-carboxylic acids (442) (Scheme 100) (59MI41600). Arbisono repeated the experiment and, when methyl c/s-cinnamate was used, in addition to the 4-carboxylic acid some 5-carboxylic acid (442) was isolated (66MI41600). The reaction of vinyl bromides with benzonitrile oxide yielded only an isoxazole and not a bromoisoxazoline (Scheme 101) (78JCR(S)192>. 

Some of the pathways of animal and bacterial metabolism of aromatic amino acids also are used in plants. However, quantitatively more important are the reactions of the phenylpropanoid pathway, which is initiated by phenylalanine ammonia-lyase (Eq. 14-45). As is shown at the top of Fig. 25-8, the initial product from phenylalanine is frans-cinnam-ate. After hydroxylation to 4-hydroxycinnamate (p-coumarate) and conversion to a coenzyme A ester, the resulting p-coumaryl-CoA is converted into mono-, di-, and trihydroxy derivatives including anthocyanins (Box 21-E) and other flavonoid compounds.The dihydroxy and trihydroxy methylated products are the starting materials for formation of lignins and for a large series of other plant products, many of which impart characteristic fragrances. Some of these are illustrated in Fig. 25-8. 

Obtain a pair of solids whose melting points are within 1 °C of one another and determine whether they indeed depress one another s melting points. Some possible examples are 3-furoic acid and benzoic acid, 1-naphthylacetic acid and 2,5-dimethyl benzoic acid, frans-cinnamic acid and 2-furoic acid, 2-methoxybenzoic acid and malic acid, or dimethyl fumarate, 9-fluorenone, and methyl 4-bromobenzoate. Consult with your instructor regarding these and other possibilities. 

Wood, W. E., Lancaster, W. C., Eisher, C. O. and Stotler, R. E. 1996. frans-Methyl cinnamate the major volatile from some populations of the liverwort Conocephalum conicum. Phytochemistry 42 241-242. 

With this procedure, N-H pyrrolidines can be synthesized directly. An important observation is that the conservation of the geometry of the dipolarophile, such as methyl cinnamate, leads to frans-Ph/COOMe pyrrolidines. This feature appears to be a general characteristic of these cycloadditions. 

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