Acetaldehyde phenyl

In the discussion of benzylamines, we have met medicinal agents that owe their activity to some particular functionality almost without reference to the structure of the rest of the molecule. The hydrazine group is one such function in that it frequently confers monamine oxidase-inhibiting activity to molecules containing that group. Such agents frequently find use as antidepressants. Thus, reduction of the hydrazone of phenyl-acetaldehyde (84) affords the antidepressant phenelzine (85). Similar treatment of the derivative of phenylacetone (86) gives pheniprazine (87). ... 

Phenyl-ethyl alcohol can be prepared by numerous methods, several of which are the subject-matter of patents. It may be prepared, for example, by the conversion of phenyl-bromo-lactic acid into phenyl-acetaldehyde, and then reducing this body with sodium. Or it may be prepared by reducing phenyl-acetic esters with sodium and absolute alcohol in the folio-wing manner —... 

It is suitable, not only for rose odours, but also for blending with almost any flower oil. Phenyl-ethyl alcohol forms a solid compound with chloride of calcium, which is very useful for its purification. On oxidation it is converted into a mixture of phenyl-acetaldehyde and phenyl-acetic acid. The last-named body forms an ethyl ester melting at 28°, which serves for its identification. 

On saponification this last compound yields vinyl alcohol and phenyl-acetaldehyde and alcohol, thus —... 

Analog erhalt man aus 2-(4-Dimethylamino-phenyl)-glyoxal-diathylacetal 2-Hydr-oxy-2-(4-dimethylamino-phenyl)-acetaldehyd-diathylacetal2 (95% d.Th. Kp0>01 106°). In Methanol als Solvens werden u.a. folgende Alkohole erhalten ... 

Bessere Ausbeuten erhalt man bei der Reduktion araliphatischer Aldehyde. Die entste-henden Alkohole kann man durch Extraktion, Rektifikation oder Wasserdampfdestilla-tion isolieren. So erhalt man z.B. aus Phenyl-acetaldehyd 61-70% d.Th. 2-Phenyl-atha-nol ... 

Condensation of phenylalaninenitrile, prepared from phenyl acetaldehyde, with 1-oxime of pyruvaldehyde afforded the pyrazine N-oxide, which was further rearranged to give the N-acetyl pyrazinone. The acetyl groups were removed by treatment with hydrazine to give the target 6-aminopyrazinone. 

Compared to the cyclic ketones, the coupling of aliphatic aldehydes to prepare 3-substituted indoles was less successful, except for phenyl acetaldehyde, which afforded 3-phenyl indole 83 in 76% yield (Scheme 4.22). The lack of imine formation or the instability of the aliphatic aldehyde towards the reaction conditions may be responsible for the inefficiency of these reactions. Therefore, a suitable aldehyde equivalent was considered. With the facile removal of a 2-trialkylsilyl group from an indole, an acyl silane was tested as a means of preparing 3-substituted indoles. Indeed, coupling of acetyl trimethylsilane with the iodoaniline 24 gave a 2 1 mixture of 2-TMS-indole 84 and indole (85) in a combined 64% yield. Evidently, the reaction conditions did lead to some desilylation. Regardless, the silyl group of 84 was quantitatively removed upon treatment with HC1 to afford indole (85). 

Run no. pH Conv. (mol%) Styrene oxide Methylated diol Diol Benzaldehyde Phenyl acetaldehyde Others... 

Such stability is only relative, however, given the possibility of the acid-catalyzed 1,2-shift of a proton observed in some olefin epoxides of general structure 10.10 (Fig. 10.3) [12], Such a reaction occurs in the in vivo metabolism of styrene to phenylacetic acid the first metabolite formed is styrene oxide (10.10, R = Ph, Fig. 10.3, also 10.6), whose isomerization to phenyl-acetaldehyde (10.11, R = Ph, Fig. 10.3) and further dehydrogenation to phenylacetic acid has been demonstrated by deuterium-labeling studies. A com-... 

Cleavage to 2-phenyl-ethylamine, phenyl-acetaldehyde and phenyl-acetic acid N-acetylation... 

Optimization of the previously reported Mannich-type reaction of trimethyl (pent-2-en-3-yloxy)silane with the sulfone Is derived from phenyl acetaldehyde (Table 5, entry 11) led to the corresponding (3-amino ketone in a good yield with moderate diastereoselectivity (2 mol% Bi(0Tf)3-4H20, yield = 84%, 24v/24v syn/anti = 72 28) (Scheme 8). Reduction of the major diastereoisomer 24v with lithium tri-ferf-butoxyaluminohydride afforded 25 as the only one diastereoisomer. Further cyclization of the latter with NaH afforded 4-benzyl-6-ethyl-5-methyl-l,3-oxazinan-2-one 26. The relative configuration of the six-membered carbamate was established as cis-cis by NMR analysis. 

The constitution of phenylalanine was determined in 1882 by Erlen-meyer and Lipp, who synthesised it by Strecker s method from phenyl-acetaldehyde, hydrogen cyanide and ammopia —... 

L Plienylalanine 10 Synthesis from phenyl acetaldehyde and resolution ... 

The rearrangement of styrene oxide into phenyl acetaldehyde was studied over various zeolites (H-ZSM-5, HY, H-offretite). It was first shown that both external and internal acidic sites are involved in that easy isomerization. Moreover, a comparative study of the rearrangement of this epoxide and of its hindered analog, 1-phenyl-1,2-epoxycyclohexene, on silanated offretite, allowed a discrimination between the activities of these sites. 

In all the isomerization reactions carried out in heterogeneous conditions, the nature of the products and product ratio depended largely on the type of catalyst employed, and, moreover, in most of the cases no selectivity was found. Papers have recently appeared concerning the transformation of styrene oxide into phenyl acetaldehyde catalyzed by a series of natural silicates and amorphous silica-alumina (ref. 15) and by pentasil type zeolites (ref. 16). It is said that, in both cases, isomerization occurs on the acidic sites (si lands) of the external surface, which act as active centers even under mild experimental conditions. 

Keywords phenyl acetaldehyde, cyclic secondary amine, salicylaldehyde, micro-wave irradiation, 2-amino-isoflav-3-ene... 

A mixture of phenyl acetaldehyde 1 (0.6 g, 5 mmol) and morpholine 2a (0.48 g, 5.5 mmol) was placed in a small beaker and irradiated in an unmodified household microwave oven at its full power (900 W) for 2 min. Salicylaldehyde 4a (0.61 g, 5 mmol) and ammonium acetate (0.02 g, 0.25 mmol) were then added to the same reaction vessel, and the reaction mixture was further irradiated in the microwave oven at its 50% power for 5 min using a pulse technique. Upon completion of the reaction, followed by TLC, the reaction mixture was passed through a bed of basic alumina using hexane-ether (9 1, v/v) as an eluent to afford pure 2-aminomorpholinoisoflav-3-enes 6a (yield 80%, mp 103-105 °C). 

The question of the fate of the "Strecker" aldehydes requires an answer. By converting the amino acid phenylalanine to yield aroma compounds, phenyl acetaldehyde is liberated. Because of its phenyl ring it is a good detector compound. We were able to establish some of its reaction products. For example, we have identified, among others, phenylethylpyrazine, phenylfuran, phenylethylpyrrole and phenylpyri-dine. We assume that aldol condensations are responsible for the formation of these compounds. Figure 5 illustrates our assumption.We have identified several compounds the structures of which make probable an aldol condensation (3-(2 -furyl)-2-phenyl-2-propenal, phenyl hydroxyketones) likely. This assumption is supported by the identification of pyrazines with up to 5 carbon atom side chains in other experiments. 

More than 300 compounds had been identified in cocoa volatiles, 10% of which were carbonyl compounds (59,60). Acetaldehyde, 2-methylpropanal, 3-methylbutanal, 2-methylbutanal, phenylacetaldhyde and propanal were products of Strecker degradation of alanine, valine, leucine, isoleucine, phenyl-acetaldehyde, and a-aminobutyric acid, respectively. Eckey (61) reported that raw cocoa beans contain about 50-55% fats, which consisted of palmitic (26.2%), stearic (34.4%), oleic (37.3%), and linoleic (2.1%) acids. During roasting cocoa beans these acids were oxidized and the following carbonyl compounds might be produced - oleic 2-propenal, butanal, valeraldehyde, hexanal, heptanal, octanal, nonanal, decanal, and 2-alkenals of Cg to C-q. Linoleic ethanal, propanal, pentanal, hexanal, 2-alkenals of to C q, 2,4-alkadienals of Cg to C-q, methyl ethyl ketone and hexen-1,6-dial. Carbonyl compounds play a major role in the formation of cocoa flavor components. 

Methyl octine carbonate Methyl heptine carbonate c/.s-3-Hexenyl methyl carbonate Nonadienal Parmavert Violet leaf absolute Liffarome Phenyl acetaldehyde glyceroacetal Fiorivert... 

Phenyl acetaldehyde with phenyl ethyl alcohol or dipropylene glycol (1 1)... 

No optical rotation is found in the recovered substances when achiral phenyl acetaldehyde or cyclohexanone is the carbonyl compound used. 

Analysis of the volatile compounds of tamarind revealed the presence of more than 80 compounds. Aromatic and furan derivatives were dominant. The major constituents were 2-phenyl acetaldehyde (25.4% of total volatiles), which has a fruity and honey-like odour, 2-furfural (20.7%), having a caramel-like flavour, followed by hexadecanoic acid (18.1%) and limonene, which has a citrus flavour. A list of the volatile compounds detected in tamarind is given in Table 20.5. 

Indole (1) Cyclization of o.amino phenyl + acetaldehyde (2) Cyclization of N-formyl, o.toluidine (3) Cyclization of N-methyl, o.toluidine... 

Thus in principle, aldehydes can be converted to ynamines through the corresponding enamines. In practice however, this is described only in the case of phenyl-acetaldehyde (43) 83). 

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