Phenylpropene derivatives

N. Hayashi et al. (1984) described a study of phenylpropene derivatives in 44 species of Heterotropa Morren Dene, growing in Japan. According to Mabberley (1997, p. 339), Heterotropa is a synonym of Asarum L., which consists of some 70 North Temperate species, 30 of which occur in Japan. Regardless of the generic... 

The reductive sequence from an appropriate cinnamic acid to the corresponding cinnamyl alcohol is not restricted to lignin and lignan biosynthesis, and is utilized for the production of various phenylpropene derivatives. Thus cinnamaldehyde (Figure 4.23) is the principal component in the... 

As mentioned above, the conversion of cyclopropane to propene radical cation has been investigated by ab initio calculations. The general course of this reaction was confirmed, or anticipated, by product studies in the electron transfer-sensitized conversion of 1,1,2,2-tetraphenylcyclopropane (37) to 1,1,3,3-tetra-phenylpropene (38). The sequence of the key steps, migration versus ring opening cannot be derived from the results. In the case of 37, the four phenyl substituents may actually favor a ring-opened bifunctional radical cation. 

The condensation (already mentioned in Section IV,B,2,a of 2-nitro-l-phenylpropene with dimedone leads to 6,7-dihydro-3-phenyl-2,6,6-trimethyl-4(5/f)-benzofuranone (321).705 c. Ichikawa Reaction.731,732 The oxymercurial derivative of propylene... 

Analogously, copyrolysis of 19 with an alcohol at 425 °C also leads to the silene-derived product, but not to the 0,H insertion product of the carbene38. The formation of 1-phenylpropene upon copyrolysis of 19 with benzaldehyde38 (equation 5) corresponds to another well-established silene-trapping reaction, namely [2 + 2] cycloaddition between... 

Cabaleiro and Johnson (1967) report that the addition of chlorine to -methyl cinnamate in chloroform or acetic acid is syn-selective, SS 0-75, in chloroform and acetic acid acetoxychloro derivatives are produced as well. Again, Dewar and Fahey (1964) argue that the normal course of addition of hydrogen halides onto olefins is a polar electrophilic process involving classical carbonium ions as intermediates and leading mostly but not exclusively to cis-adducts. A syn-preference was found in the additions of deuterium bromide to acenaphthylene, indene, and cis- and fraws-phenylpropene. In the case of indene, phenylpropene and methyl cinnamate, which are styrene analogs, concerted syn addition is symmetry-allowed (see bottom of p. 273). 

In rare instances, hydroaminomethylation can occur by using electron-rich alkenes such as styrene derivatives. Thus, 1-phenylpropene added Me3N regioselec-tively to form N,N-dimethyl-2-phenylbutan-l-amine upon excitation via a styrene-amine exciplex [24]. 

The reaction rate of the addition decreased on going from phenyl-substituted alkenes to mono-, di-, and trisubstituted alkenes. A preference for E double bonds over Z double bonds was exhibited by the monoimido complex 1. Complete regioselectivity was observed with mono-and trisubstituted alkenes and gmi-disubstituted alkenes, since the C-N bond is formed exclusively at the least substituted alkene carbon, for example of 1-methyl- and 1-phenylcyclo-hexene. However, for 1,2-disubstituted alkenes the regioselectivity depended on the substrate70,71. Unexpectedly, benzylic amination was predominant in the reaction mixtures derived from 1-phenylpropenes and 1,2-dihydronaphthalene (Tabic 5). 

When allylic hydrogens are present in the alkene, A-allyl hydrazine derivatives are formed preferentially by the ene reaction (Section 7.6.). Furthermore, the reaction of styrenes, (Ey -phenylpropene, and stilbenes with diazenedicarboxylates (traditionally known as azodicar-boxylates) and triazolediones affords products involving double Diels-Alder or Diels-Alder-ene reactions (Section 7.2.10.3.3.). 

It has been noted that the chemical diversity of plant phenolics is as vast as the plant diversity itself. Most plant phenolics are derived directly from the shikimic acid (simple benzoic acids), shikimate (phenylpropanoid) pathway, or a combination of shikimate and acetate (phenylpropanoid-acetate) pathways. Products of each of these pathways undergo additional structural elaborations that result in a vast array of plant phenolics such as simple benzoic acid and ciimamic acid derivatives, monolig-nols, lignans and lignin, phenylpropenes, coumarins, stilbenes, flavonoids, anthocyanidins, and isollavonoids. 

Pyrazine derivatives have been obtained on pyrolysis of a-sub-stituted vinyl azides in ethanol. Thus l-azido-2-phenylpropene (305) produced 2,5-dimethyl-2,5-diphenyldihydropyrazine (306) (48%) on... 

Blank, B., Zuccarello, W.A., Cohen, S.R., Frishmuth, G.J., and Scaricaciottoli, D., Synthesis and adrenocortical inhibiting activity of substituted diphenylalkylamines, J. Med. Chem., 12, 271, 1969. Ferreira, A.B.B., and Salisbury, K., The photochemistry of l-cyano-2-methyl-3-phenylpropene and ring substituted derivatives, J. Chem. Soc., Perkin Trans. 2, 25, 1982. 

Numerous papers have been published describing the photochemical production of enones from carbonyl compounds and alkynes. The first detection of an oxetene intermediate involved low-temperature (-78 C) photolysis of 2-butyne and benzaldehyde to form the photoproduct (61), which was observed by NMR. llie oxetene undergoes further photoreaction with benzaldehyde to form the novel fused oxetane (62). Recently, Friedrich has reported Anther studies on the reactivity of oxetenes and developed alternative syntheses of the parent compound and 3-phenyloxete (64). The parent oxetene is found to have a themial half-life of approximately 8 h in solution at room temperature. The phenyl-substituted derivative (64) underwent slow ring-opening under acidic conditions to form 2-phenylpropenal and air oxidation to yield a formate derivative, probably via a radical process. 

Another attractive feature of the phosphonamide route is that it can be controlled to give cis- and trans-olefins.4 Formation of the adduct is not stereospecific, but the elimination reaction is stereospecific (cis cycloelimination). The synthesis of cis- and trans-1 -phenylpropene is illustrative the former was prepared from the reaction of benzaldehyde with the a-lithio derivative of ethylphosphonic acid bis(dimethyl-amide) to give two diastereoisomeric /3-hydroxyphosphonamides (5) in the ratio of 3.5 1. The major isomer was separated by crystallization and on pyrolysis gave cis-1 -phenylpropene. The isomeric olefin was prepared by reaction of the a-lithio... 

The formylation of styrene derivatives has been extended to several related alkene derivatives indene (52) gives 2-formylindene (53 20%), polyenes (54) and (55) afford aldehydes (56 92%) and (57 29-65%), and fulvene derivative (58) yields (59). In several cases, the products of monosubstitution described above are accompanied by products of polysubstitution, particularly under forcing conditions. For example, 2-phenylpropene reacts with salt (1) to give 4-phenylpyridine-3-carbaldehyde (60) after treatment with aqueous ammonium chloride solution. A useful synthesis of biphenyls (61 30-98%) from alcohol derivatives (62) and salt (1) has recently been reported. ... 

Photocycloaddition of 2-methyl- and 2-ethyl-naphthoquinone to styrene yields three cyclobutane products (457,458) in which the 8-phenylisomer dominated. " The ratio of 7-phenyl to 8-phenyl products was 1 6 for the methylquinone and 1 3.5 for the ethyl derivative. The authors suggest that in these examples dipole-dipole interactions overcome any adverse repulsions. Changes in the olefin brings about changes in the ratio of products. Thus with 2-phenylpropene the ratio... 

In the absence of Br and at low concentrations of Br2, the kinetic expression is first order in alkyne and first order in bromine. A p value of —5.17 for bromine addition to substituted derivatives of 56 is consistent with the intermediacy of a vinyl cation-bromide ion pair that can combine to form both cis and trans dibromide adducts or can react with solvent to form cis- and traMS l-acetow-2-bromo-l-phenylpropene, as shown in equations 9.58 through 9.60. - ... 

Lignans are C-18 natural compounds formed essentially by the union of two molecules of phenylpropene (C-6, C-3) formed from cinnamate derivatives. Lignans are optically active compounds and the union takes place between the middle carbons of the monomers side chains. Important pharmaceutical examples are the lignans of Podophyllum... 

The phenolic primary alcohols derived in this way from phenylalanine (Phe, F) and in some systems from tyrosine (Tyr, Y) are incorporated into structural plant materials by linking carbohydrates (Chapter 11) together to form Ugnins. The same alcohols give rise to phenylpropenes, such as eugenol and safrole, which are commonly referred to as essential oils, while further oxidation and double-bond isomerization of p-coumaric acid leads to umbeUiferone (Figure 12.6). 

Hydroxybenzoic and vanillic acids are also present in numerous fruits and vegetables [1], and the native forms are frequently simple combinations with glucose (Table 1). Other derivatives have been detected in certain fruits [1,2] the methyl ester of />-hydroxybenzoic acid in passion fruit, 3,4-dihydrox-ybenzoic aldehyde in banana, a phenylpropene benzoic acid derivative in fruits of Jamaican Piper species, and benzoyl esters and other derivatives in the fruits of Aniba riparia. Different new glycosides of HBA showing radical-scavenging activity [e.g., a new guaiacylglycerol-vanillic acid ether (Fig. 1)] have been identified in the fruits of Boreava orientalis [20]. 

Phenylpropenes are derived from cinnamic acid and share the first steps of lignin/lignan biosynthesis. Shortening of the cinnamic acid side chain by two carbons leads to compounds with a C -C skeleton called benzenoids. Other volatile... 

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