3- Oxoglutaric acid

Animals caimot synthesize the naphthoquinone ring of vitamin K, but necessary quantities are obtained by ingestion and from manufacture by intestinal flora. In plants and bacteria, the desired naphthoquinone ring is synthesized from 2-oxoglutaric acid (12) and shikimic acid (13) (71,72). Chorismic acid (14) reacts with a putative succinic semialdehyde TPP anion to form o-succinyl benzoic acid (73,74). In a second step, ortho-succmY benzoic acid is converted to the key intermediate, l,4-dihydroxy-2-naphthoic acid. Prenylation with phytyl pyrophosphate is followed by decarboxylation and methylation to complete the biosynthesis (75). 

Oxoglutaric acid (2-oxopentane-l,5-dioic, a-ketoglutaric acid) [328-50-7] M 146.1, m 114 , 115-117 , (pK ,( see oxaloacetic acid above). Crystd repeatedly from Me2CO/ benzene, EtOAc or ethyl propionate. 

The thallium benzoate and thallium 2-oxocarboxylates are available via the reaction of thallium acetate with benzoic acid or the 2-oxocarboxylic acids, due to the lower values of these acids (benzoic acid 4.22, benzoylformic acid 1.2, 2-oxoglutaric acid 31/5.14, pyruvic acid 2.49) compared to acetic acid (4.76) (167). The free acetic acid is distilled off with water as an azeotrope and the thallium carboxylates are obtained in high purity. 

In a 250 mL flask equipped with a stir bar were introduced 4-methyl-2-oxoglutaric acid 1 (0.5 g, 2.9 mmol), CSA (0.45 g, 2.9 mmol), water (145 mL) and acetaldehyde (128 mg, 2.9 mmol). The pH of the solution was adjusted to 7.6 with 1 m KOH before the addition of pig heart Asp AT (1 mg). The commercial enzyme suspension in 3 M (NH4)2S04 was centrifuged (5 min at 10 000 rpm), the supernatant eliminated and the enzyme pellet dissolved in the reaction mixture. The reaction was stirred slowly at room temperature and monitored by titration of pyruvic acid formed from CSA. 

The pH-dependent equilibrium 8A 8B, involving participation of the open-chain tautomer hydrate, was observed [75JBC(250)527] in aqueous solutions of 2-oxoglutaric acid. 

N-Alkylated 2-oxoglutaric acid derivatives cyclize at neutral pH values to two epimeric 5-carboxy-5-hydroxy-2-oxopyrolidine structures (Chart 4). In this way, ot-hydroxycarboxylic acid groupings are formed that can act as ligand sites for Fe ". ... 

The second function, and the one pertinent to this section, is the decarboxylation of oxalosuccinic acid to 2-oxoglutaric acid. This is simply a biochemical example of the ready decarboxylation of a P-ketoacid, involving an intramolecular hydrogen-bonded system. This reaction could occur chemically without an enzyme, but it is known that isocitric acid, the product of the dehydrogenation, is still bound to the enzyme isocitrate dehydrogenase when decarboxylation occurs. 

GABA acts as an inhibitory transmitter in many different CNS pathways. It is subsequently destroyed by a transamination reaction (see Section 15.6) in which the amino group is transferred to 2-oxoglutaric acid, giving glutaric acid and succinic semialdehyde. This also requires PLP as a cofactor. Oxidation of the aldehyde group produces succinic acid, a Krebs cycle intermediate. 

The reaction of alloxane hydrate (342) and 46a,c gives 100% yield of the products 343a,c upon milling at room temperature [104]. The solid-state reaction of 2-oxoglutaric acid (344) and 46a similarly gives a quantitative yield of the quinoxalinone 345 in the solid state upon heating of coground mixtures for 30 min to 120-125 °C [104]. 

Heating chloroacrolein yields 20% of 6-chloro-2-formyl-4//-pyran.l92The formation of pyrans by thermal decomposition of ethyl acetoacetate and its homologs on a copper powder catalyst is patented.193 Surprisingly, 2H-pyran 148 (20%) was reported when 2-oxoglutaric acid reacted with lead(II) nitrate.194... 

Keywords o-phenylendiamine, 2-oxoglutaric acid, cyclization, cascade reaction, waste-free, solid-solid reaction,2-quinoxalinone... 

Transamination. Transamination with pyridoxal or analogs requires a metal catalyst such as Cu(II). However, transamination can be effected with DPL in combination with hexadecyltrimethylammonium chloride. By using these two reagents phenylglycine undergoes transamination with 2-oxoglutaric acid (equation I). 

A biomimetic synthesis of solerone (5-oxo-4-hexanolide) 1 using both enzymatic and acid-catalyzed reactions was performed. Starting from L-glutamic acid 5-ethyl ester 2 enzymatic oxidative deamination followed by subsequent decarboxylation of the corresponding 2-oxoglutaric acid 5-ethyl ester 3 led to ethyl 4-oxobutanoate 4. In the presence of pyruvate,... 

While in the presence of 2-oxoglutaric acid neither decarboxylation nor acyloin condensation had been observed, as expected from previously published results (75), we succeeded in the enzymatic conversion of the mono ethyl ester 3 to ethyl 4-oxobutanoate 4, using both whole yeast cells (Saccharomyces cerevisiae) and purified PDC. The oxo ester 4 served as substrate for a second reaction catalyzed by PDC. Formation of a new carbon-carbon bond was accomplished in the presence of pyruvic acid which acted as donor of a C2-unit. Thus, ethyl 4-hydroxy-5-oxohexanoate 5 was obtained for the first time as the result of an enzymatic acyloin condensation. Finally, traces of acid induced the lactonization of hydroxyester 5, indicating it as direct precursor of solerone 1 (Figure 1). 

The sodium salt of the stabilized enolate derived from the heteroaryl-substituted 2-oxoglutaric acid ester (186) is reported to have the alkene geometry as shown in formula (187). Hnally, Collum et al. have reported the structure of the lithiated anion derived from the A, A -dimethylhydrazone of 2-methoxy-carbonylcyclohexanone (188). This enolate crystallizes as the dimeric, bis-THF-solvated aggregate (189). 

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