Phenylglyoxalates

The anaerobic metabolism of L-phenylalanine by Thauera aromatica under denitrifying conditions involves several steps that result in the formation of benzoyl-CoA (a) conversion to the CoA-ester by a ligase, (b) transamination to phenylacetyl-CoA, (c) a-oxidation to phenylglyoxalate, and (d) decarboxylation to benzoyl-CoA (Schneider et al. 1997). 

Hirsch W, H Schagger, G Fuchs (1998) Phenylglyoxalate NAD+ oxidoreductase (CoA benzoylating), a new enzyme of anaerobic phenylalanine metabolism in the denitrifying bacterium Azoarcus evansii. Eur J Biochem 251 907-915. 

Diethylmalonate anion does not apparently react cleanly with dioxygen and in this case a complex mixture of products of self-condensation is obtained. However substituted diethylmalonates are usefully converted into hydroxylated products. In the case of diethyl phenylmalonate conversion into the corresponding carbonyl compound, ethyl phenylglyoxalate, was observed — presumably according to the mechanism given in Scheme 19. 

J. Houben obtained methane, etc., by the action of magnesium alkyl haloids on the hydrazines the action of zinc ethyl and magnesium alkyl haloids on hydrazine has been studied by R. L. Krause the action of mono- and di- chloroacetic acids, by Jit. Busch and E. Meussdorffer ethyl chloroacetate, by A. Reissert and W. Kayser, and M. Busch and eo-workers phenylglyoxalic acid, by A. Elbers dinitrophenylhydrazine, by T. Curtius and M. Mayer ethyl dinitrobenzoate, by T. Curtius and A. Riedel dinitrobenzoic add, by T. Curtius and H. E. Bollenbach nitro- and amido-phthalhydrazides, by T. Curtius and A. Hoesch formaldehyde, by E. Riegler, and E. Rimini carbonyl compounds, by... 

The biradical benzo-l,2 4,5-bis(l,3,2-dithiazolyl) (BBDTA) is known in the literature but characterization is incomplete. A new study reports the electronic, molecular, and solid-state structure of BBDTA.224 The lifetime of an alkyl phenylglyoxalate-derived 1,4-biradical has been estimated, using the cyclopropylmethyl radical clock , to be in the range 35—40 ns.225 The indanols (88) and their C(3) methyl and trideuteromethyl analogues have been prepared from phenyl benzyl ketone via photo-cyclization of an intermediate 1,5-biradical species.226,227 Selectivity for these products over their C(l) epimers is high but is profoundly effected by substitution in the benzyl ring or the alkyl side-chain. The findings are rationalized in terms of the conformational preference of the intermediate 1,5-biradicals. 

The benzyl hydroxyl containing API cyclandelate undergoes oxidation to the corresponding ketone, 3,3,5-trimethylcyclohexyl phenylglyoxalate (143). Low level benzylic oxidation is observed for the API ibuprofen. Oxidation to form the ketone derivatives at both benzylic sites to yield isobutyl acetophenone and 2-(4-isobutyrylphenyl)-propionic acid has been reported (144). 

Optically active a-hydroxy carboxylic acids. The organozinc reagents prepared in situ from RMgX and ZnCl2 or ZnBr2 add selectively to the keto group of - l-menthyl phenylglyoxalate (1). The adducts are hydrolyzed to optically active a-hydroxy carboxylic acids (3).1... 

Oxidation of esters of a-amino acids. These substrates are oxidized by the Mitsunobu reagent (1) at the a-position to give either a-keto esters or adducts. For example, the N-benzyloxyphenylglycine methyl ester 2 is oxidized to methyl phenylglyoxalate 3 in 93% yield. In contrast, reaction of N-formylphenylglycine methyl ester (4) results in a triazoline (5) in 80% yield. ... 

The structure and absolute stereochemistry of yohimbine (V) have been known for some time (Volume VII, p. 50). The absolute configuration at C-17 has been determined by the method of Prelog, as follows the phenylglyoxalate of yohimbine (VI), on treatment with methyl magnesium bromide, generated an ester (VII) which on hydrolysis gave a substantial yield of L-( + )-atrolactic acid (VIII) (3). 

Regioselective photocyclization of ethylthiopropyl phenylglyoxalate 793, by an electron-transfer process, produced the 1,5-oxathiocin 773 in 96% yield. The mechanism proposed for such a photocyclization involved excitation of the keto ester 793 to its triplet state (T) upon irradiation (350 nm), and electron transfer between the donor and acceptor occurred in T producing the ketyl radical anion (A). This was deactivated to ground state 793 by back electron transfer or was converted to biradical (B) by proton transfer process. Cyclization occurred between the excited carbonyl group and the carbon a to the sulfur on the remote side (Scheme 156) <1997T7165>. 

Figure 6.9. Temperature dependence of the diastereoselectivity of oxetane formation (22 , 23 A, 24 ) by cycloaddition of menthyl phenylglyoxalate (19) to tetra-methylethylene (20) and ketene acetal (21) (by permission from Biischmann et al., 1991).

The addition of benzophenone, for example, affords low yields of the four isomeric oxetanes (66, R = Ph), (67, R = Ph), (68) and (69). These addition reactions take place in competition with the conversion of the alkene into (70) and (71). The conversion to these alkenes presumably is the result of energy transfer from the excited ketone. The addition of methyl phenylglyoxalate to the alkene (65) affords a single adduct (72) in 70% yield while the addition of benzil to the same alkene yields the two adducts (66, R = PhCO, 31%) and (67, R = PhCO, 6%) ... 

The photochemical reactions of ethyl phenylglyoxalate (217) in benzene have been re-examined. The three new products (218), (219) and (220) have been isolated from the reaction mixture. The quantum yields for the formation of the products are dependent on concentration. Irradiation of the phenylglyoxalate derivatives (221) results in conversion into the lactones (222) from (221, R = H) and (223) and (224) from (221, R = Me). The reactions are proposed to involve an intramolecular electron transfer process forming a zwitterionic biradical. This leads to activation of the methylenes adjacent to the sulfur atom. A similar effect is observed with the nitrogen analogue (225) which affords (226) as the... 

A procedure for the synthesis of semicarbazone from phenylglyoxalic acid was studied.[2]... 

A number of low molecular weight products, for example, benzaldehyde, formic acid, formaldehyde, phenylglyoxal, phenylglyoxalic acid, and carbon dioxide, were identified among the products of thermal decomposition of the ozonides. A determination of the detailed structure of the polymer is possible from the qualitative analysis of these decomposition products. 

Berghauser and Falderbaum (213) used phenylglyoxalate to inactivate LDH. They found that one arginyl residue per subunit was modified. In both these cases ternary complexes protected modification of arginines. Since the modified enzyme could bind coenzyme but could not form a... 

---