Aldehyde phenylacetaldehyde

Benzaldehyde is an important intermediate for dyes (see malachite green) many other aldehydes (phenylacetaldehyde, vanillin, piperonal, citral, etc.) are used in perfumery or as flavouring agents. 

A great many aldehydes can be employed—propaldehyde, nitrobenz-aldehyde, phenylacetaldehyde, furfurol—so that the reaction is of wide application. For the steps in the conversion of the compounds obtained to alkyl or aryl derivatives of dimethylpyridine, see pp. 242, 411, 412. 

The dianion of the hydroxybutyrolactone (87) reacts with aldehydes with high diastereofacial selectivity to give mixtures of dihydroxy lactones (88) and (89) (equation 76 Table 5). ° The lithium enolate shows little simple stereoselection with the sterically undemanding aldehydes phenylacetaldehyde and tetradecanal. Significant stereoselectivity is seen in the reaction with benzaldehyde, and pivalaldehyde gives only a single product. Because the aldol relative stereochemistry in the reactions with benzalde-... 

When the aromatic aldehyde is omitted from a Biginelli reaction mixture, a dihydropyrimidine is still formed. Thus, for example, phenylacetaldehyde (2 mol) and urea (1 mol) react to give 4-benzyl-5-phenyl-3,4-dihydropyrimidin-2(li/)-one (676) (33JA3361). 

Styrene oxide [96-09-3] M 120.2, b 84-86 /16.5mm, d 1.053, n 1.535. Fractional distn at reduced pressure does not remove phenylacetaldehyde. If this material is present, the styrene oxide is treated with hydrogen under 3 atmospheres pressure in the presence of platinum oxide. The aldehyde, but not the oxide, is reduced to 6-phenylethanol) and separation is now readily achieved by fractional distn. [Schenck and Kaizermen J Am Chem Soc 75 1636 1953.]... 

A few other aldehydes have been used in the reaction, either under normal or pseudo-physiological conditions. Of these, glycolalde-hyde, 5-hydroxypentanal, phenylacetaldehyde, and benzalde-hyde condense readily, but hydroxy and methoxy derivatives of these aromatic aldehydes give the product in poor yield,presumably due to their instability, as evidenced by their tendency to undergo self-condensation in acid solution. Reaction with phthaldehydic acids, such as opianic acid, proceeded readily, whereas reaction with chloral did not occur,... 

Solution The spectrum shows an intense absorption at 1725 cm- due to a carbonyl group (perhaps an aldehyde, -CHO), a series of weak absorptions from 1800 to 2000 cm-1, characteristic of aromatic compounds, and a C—H absorption near 3030 cm-1, also characteristic of aromatic compounds. In fact, the compound is phenylacetaldehyde. 

Condensation of the carbanion of optically active p-tolyl p-tolylthiomethyl sulphoxide 380 with benzaldehyde and phenylacetaldehyde produces the corresponding sulphoxides 432 which are converted into optically active a-methoxy aldehydes 433 and alcohols 434 with enantiomeric excess of 70% and 46%, respectively506,507 (equation 259). 

Many aldehyde reductases transform both aldehydes and ketones. For example, phenylacetaldehyde reductase (PAR) from a styrene-assimilating Corynebacterium strain, ST-10, reduces hexyl aldehyde and phenylacetaldehyde [22aj. Other aldehyde reductases such as one from Sporobolomyces salmonicolor also reduce aldehydes as well as ketones [22b]. 

The phenylacetaldehyde reductase involved in the degradation of styrene is also able to accept long-chain aliphatic aldehydes and ketones, and halogenated acetophenones (Itoh et al. 1997). 

In the presence of the indane aldehyde, additional somewhat irreversible waves are seen at ( wO.l V), which probably refer to some Ru(III) intermediates (10) involved in the catalysis. In the corresponding phenylacetaldehyde system, additional waves are seen at about -0.08 and +0.08 V. On adding nBuoP to the indane aldehyde system, waves are seen at 0.30 V [RuIII(TPP)(nBu3P)2 + e RuII(TPP)(nBu3P)2]> and M).90 V [due to the couple shown... 

A new, fast, sensitive, and solventless extraction technique was developed in order to analyze beer carbonyl compounds. The method was based on solid-phase microextraction with on-fiber derivatization. A derivatization agent, 0-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine (PFBOA), was absorbed onto a divinyl benzene/poly(dimethylsiloxane) 65- xm fiber and exposed to the headspace of a vial with a beer sample. Carbonyl compounds selectively reacted with PFBOA, and the oximes formed were desorbed into a gas chromatograph injection port and quantified by mass spectrometry. This method provided very high reproducibility and linearity When it was used for the analysis of aged beers, nine aldehydes were detected 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, pentanal, hexanal, furfural, methional, phenylacetaldehyde, and (E)-2-nonenal. (107 words)... 

The aldehydes 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, methional, and phenylacetaldehyde are so-called Strecker aldehydes, formed as a result of a reaction between dicarbonyl products of the Amadori pathway and amino acids, having one less carbon atom than the amino acid (i). 

Further investigation with various silyl ketene acetals is summarized in Table 6. Silyl ketene acetals derived from various esters were reacted with /V-benzyloxy-carbonylamino sulfones 1 in the presence of 0.5-1 mol% Bi(0Tf)3-4H20. The corresponding (3-amino esters 24 were obtained in moderate to good yields (Table 6). Silyl enolates derived from esters as well as thioesters reacted smoothly to give the adducts. The /V - be n z v I o x v c ar bo n v I a m i n o sulfone derived from n-butvraldehyde lp led to moderate yields of (3-amino esters when reacted with (thio)acetate-derived silyl ketene acetals (Table 6, entries 1 and 2). A very good yield was obtained when the same sulfone was subjected to a tetrasubstituted silyl ketene acetal (Table 6, entry 3). The latter afforded moderate to good yields of (3-amino esters 24 with phenylacetaldehyde, / -tolu aldehyde, and o-tolualdehyde-derived sulfones (Table 6, entries 4-6). 

An additional indication of the mildness of the cyclization is provided by the synthesis of the chiral tetrahydroisoquinoline-3-carboxylic acid (294) (72HCA15) in the presence of hydrogen and palladium-on-charcoal the jV-methyl derivative was obtained. Acetaldehyde gave a mixture of diastereoisomers in which the cis isomer (295) predominated (95 5). Unstable aldehydes can sometimes be generated in situ, as when the phenylglycidate (296) replaces the much less stable phenylacetaldehyde (66T(S8)129) acetals, enol ethers and chloromethyl methyl ethers have also been used. The mild conditions also allow the isolation of 4-hydroxytetrahydroisoquinolines (297) (75H(3)311). A review is available listing syntheses of 4-oxytetrahydroisoquinolines (73AHC(15)99). 

Choice of THF as the solvent, Me2PhSiH as the hydrosilane, and operation under anhydrous conditions are critical for selective silylformylation of 121 to give 122, whereas these regulations are not necessary in the silylformylation of alkynes. Similar silylformylation is applied to 2-(iV-methylpyrrolidyl)aldehyde (60%), 2-furylaldehyde (90%), 2-thiophenecarboxaldehyde (72%), 2,6-dimethyl-5-heptenal (60%), butanal (60%), 2-methylpropanal (75%), ferrocenecar-boxaldehyde (88%), and phenylacetaldehyde (80%) ... 

There are several other examples of the use of indene derivatives as a source of isocoumarins. Alkaline decomposition of the cyclic peroxide (507), produced by ozonolysis of indene itself, yields a phenylacetaldehyde (57JA3165). Treatment of these aldehydes with acid gives access to isocoumarins which are unsubstituted in the pyranone ring (65JIC211). 

An interesting means of improving the selectivity of Pd for the conversion of unconjugated dienes, such as 1,4-cyclooctadiene to the monoene is to add phenylacetaldehyde to the mixture undergoing reaction (ref. 36). The mechanism of action is not established but it may involve aldehyde decarbonylation to form adsorbed CO but the addition of small amounts of CO to the reactants does not reproduce the effect of the aldehyde (ref. 37). Means to modify the metal suface in other ways can prove effective, the studies of Ni catalysts by Okamoto et al. afford an interesting example of an attempt to reach a more fundamental understanding of catalyst selectivity. 

A problem associated with beef sterilized by irradiation at approximately room temperature is the production of an unpleasant flavor and aroma. This paper summarizes knowledge of the volatile components of enzyme-inactivated irradiated and nonirradiated beef, reviews the effects of concurrent and nonconcurrent irradiation procedures and of storage on these components, and presents evidence that methional (3-methylmercaptopropion-aldehyde), 1-nonanal, and phenylacetaldehyde are of primary importance to irradiation off-odor in beef thus processed. 

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