Phenylacetaldehyde, from

Periodic acid dihydrate, with iodine and durene to give iododurene, 51, 94 Phenols, from aryl methyl ethers, 53, 93 Phenylacetaldehyde, from 2-lithio-1,3,5-trithiane and benzyl bromide, 51, 43 Phenylacetic acid, bromination, 50, 31... 

Aldehydes related to common amino acids (3-methylbutanal from leucine, 2-methylpropanal from valine, phenylacetaldehyde from phenylalanine) are formed by enzymatic decarboxylation of the corresponding keto acids, which in turn are reversibly related to the amino acids by transamination [i.e., the keto acids are both degradation products of amino acids 147, 148) and intermediates in their synthesis 149). A third possibility—non-enzymatic oxidation of amino acids to aldehydes by enzymatically produced o-quinones—is established 150, 151) but is not discussed here. 

A final mechanism for the formation of carbonys via nticroorganisms involves the transamination and decarboxylation of free amino acids. Morgan [95] has demonstrated the production of 3-methyl butanal by S. lactis var. maltigenes (Figure 5.10). MacLeod and Morgan [96] have demonstrated the production of 2-methyl butanal, methional and phenylacetaldehyde from leucine, methionine and phenylalanine, respectively, by the same microorganism. 

Phenylacetaldehyde from Benzylinalonic Ester. A mixture of 100 g. of ethyl benzylmalonate, 50 g. of hydrazine hydrate, and 10 cc. of absolute ethanol is refluxed for six hours on a steam bath. The dihydrazide is filtered from the cooled mixture and washed with a little ethanol and ether after drying on a clay plate and then in vacuum, the crude product weighs 91-91.5 g. (ca. 100%) and melts at 164°. A solution of 11.1 g. of this dihydrazide in a cold solution of 9.8 g. of concentrated sulfuric acid in 44 cc. of water is covered with 50 cc. of ether and cooled to —5° in an ice-salt bath. A solution of 10.35 g. of sodium nitrite in 21 cc. of water is added slowly with stirring, the ether layer is then separated, and the aqueous phase is extracted once with ether. After the combined ethereal extracts have been dried for one hour over sodium sulfate at 0°, 100 cc. of absolute ethanol is added, and the mixture is refluxed for three hours during this time most of the ether is allowed to escape. The resulting solution of the srewi-diurethan is concentrated to a syrup and allowed to crystalhze in vacuum over sulfuric acid yield, 10.5 g. (75%) m.p. 166°. (If the next step is to be performed immediately, the crystallization is unnecessary.)... 

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). 

ICj Preparation of 3-Bemyl-6-Trifluoromethyl-7-Sulfamyl-3,4-Dihydro-1, 4 Ben othiadiazine 1,1-Dioxide A grams of 5-trifluoromethyl-2,4-disulfamylaniline is dissolved in 12 ml of dioxane. 2.7 ml of phenylacetaldehyde and a catalytic amount of p-toluenesulfonic acid are added. After boiling for a short time under reflux, the reaction mixture crystallizes, and, after filtration and recrystallization from dioxane, the desired product is obtained with a MP of 224.5°-225.5 C,... 

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. 

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]. 

Figure 8.35 Reduction of ketones with phenylacetaldehyde reductase from Corynebacterium strain ST-10 [26].

Chromyl chloride oxidation of alkenes proceeds via the formation of adducts at a rate necessitating stopped-flow techniques. At 15 °C the formation of 1 1 adduct from styrene and oxidant in CCI4 solution is simple second-order with 2 = 37.0 l.mole .sec . Measurements with substituted styrenes yielded = — 1.99. E = 9.0 kcal.mole and = —23.8eu for styrene itself. Hydrolysis of the styrene adduct yields mostly phenylacetaldehyde (76.5 %)and benzaldehyde (21.1 %). Essentially similar results were obtained with a set of 15 alkenes and... 

For cinnamic acid at 9.6 °C, a = 0.107, b = 1.25 and k = 0.69 l.mole .sec E = 26.7 0.5 kcal.mole" and AS = 34.5 eu. Identification of products of oxidation of a number of acids indicates two concurrent mechanisms. Predominating is direct attack on the double bond to give, ultimately, cleavage products, e.g. benzaldehyde from cinnamic acid (some phenylacetaldehyde is also found, indicating oxidative decarboxylation to occur) and also acetophenone from 3-phenylcrotonic acid. 

Itoh N, R Morihama, J Wang, K Okada, N Mizngnchi (1997) Pnrification and characterization of phenylacetaldehyde reductase from a styrene-assimilating Corynebacterium strain, ST-10. Appl Environ Microbiol 63 3783-3788. 

No stereoselectivity was observed in the formation of a 1 1 diastereomeric mixture of 2-hydroxy-2-phenylethyl p-tolyl sulfoxide 145 from treatment of (R)-methyl p-tolyl sulfoxide 144 with lithium diethylamide . However, a considerable stereoselectivity was observed in the reaction of this carbanion with unsymmetrical, especially aromatic, ketones The carbanion derived from (R)-144 was found to add to N-benzylideneaniline stereoselectivity, affording only one diastereomer, i.e. (Rs,SJ-( + )-iV-phenyl-2-amino-2-phenyl p-tolyl sulfoxide, which upon treatment with Raney Ni afforded the corresponding optically pure amine . The reaction of the lithio-derivative of (-t-)-(S)-p-tolyl p-tolylthiomethyl sulfoxide 146 with benzaldehyde gave a mixture of 3 out of 4 possible isomers, i.e. (IS, 2S, 3R)-, (IS, 2R, 3R)- and (IS, 2S, 3S)-147 in a ratio of 55 30 15. Methylation of the diastereomeric mixture, reduction of the sulfinyl group and further hydrolysis gave (—)-(R)-2-methoxy-2-phenylacetaldehyde 148 in 70% e.e. This addition is considered to proceed through a six-membered cyclic transition state, formed by chelation with lithium, as shown below . ... 

Phenylacetyl chloride and hydrocin-namoyl chloride are reduced at mercury to form both acyl radicals and acyl anions as intermediates [76]. From electrolyses of phenylacetyl chloride, the products include 1,4-diphenyl-2-butene-2,3-diol diphenylac-etate, phenylacetaldehyde, toluene, 1,3-diphenylacetone, and l,4-diphenyl-2,3-butanediol, and analogous species arise from the reduction of hydrocinnamoyl chloride. Reduction of phthaloyl dichloride is a more complicated system [77] the electrolysis products are phthalide, biph-thalyl, and 3-chlorophthalide, but the latter compound undergoes further reduction to give phthalide, biphthalyl, and dihydrobi-phthalide. 

Chemicals. The carbonyl compound standards 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, pentanal, hexanal, furfural, methional, phenylacetaldehyde, and (E)-2-nonenal were purchased from Sigma-Aldrich (Milwaukee, Wl). A stock solution containing a mixture of the standard compounds in ethanol was prepared daily in a concentration of 100 ppb each. An aqueous solution of the derivatization agent 0-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine (PFBOA) (Sigma-Aldrich, Milwaukee, WI) was prepared at a concentration of 6 g/L. PFBOA solution was prepared every 3 months and kept refrigerated. 

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). 

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