A-ketopimelate

Incubations of cell suspension cultures of Idesia polycarpa and of seed tissue ofH. anthelminthic a with [l,2- C]a-ketopimelate proved the validity of the Cl chain elongation mechanism. Although in the systems tested this substrate was metabolized to some extent, cyclopentenylglycine was synthesized at a much higher rate from a-ketopimelate than from acetate. In a control experiment, cell suspension cultures of soya were incubated with [l,2- C]a-ketopimelate or [l- C]acetate, but cyclopentenylglycine was not synthesized in either case (Tober and Spener, 1980). 

Heat. When heated, succinic acid loses water and forms an internal anhydride with a stable ring stmcture. Dehydration starts at 170°C and becomes rapid at 190—210°C (25). Further heating of succinic anhydride causes decarboxylation and the formation of the dilactone of gamma ketopimelic acid (26) (eq. 1). The same reaction takes place at lower temperatures in the presence of alkaU. 

A. Diethyl oi-acelyl-fi-ketopimelate. In a 2-1. three-necked flask equipped with a merauy-sealed Hershberg stirrer, a dropping funnel, and a reflux condenser protected with a caldum chloride tube are placed ll.S g. (0.5 g. atom) of finely powdered sodium (Note 1) and 500 ml. of dry ether. The flask is placed in an ice bath, and 65.0 g. (63.5 ml., 0.5 mole) of freshly distilled ethyl acetoacetate in 150 ml. of dry ether is slowly added from the dropping funnel with stirring (approximate time for addition is 30-40 minutes). The mixture is stirred overnight, then it is... 

The distillate contains mostly C-acyl ester with a little of 0-acyl ester. Separation of these two esters by means of a carbonate solution in which only the C-acyl ester is soluble is possible. This separation is unnecessary in the present procedure for the 0-acyl derivative gives rise to ethyl acetoacetate during decomposition with ammonia. This low-boiling ester is removed during the distillation of diethyl -ketopimelate. 

The described method of preparing diethyl jS-ketopimelate is a modification of that described by Bouveault and is essentially the same as that reported by Bardhan and Nasipuri. This ester has also been prepared by condensation of 7-carbethoxybutyryl chloride with ethoxymagnesiummalonic ester and cleavage of the resulting acylated malonic ester by (3-naphthalenesulfonic add or by acetic or propionic acids containing a trace of concentrated sulfuric acid. ... 

The present method offers a more convenient synthesis with appreciably higher yields of diethyl /3-ketopimelate. It is reported to be useful for the preparation of dimethyl /3-hetoadipate and diethyl /3-ketosubcrate. ... 

IDegradation. Heating of succinic acid or anhydride yields y-ketopimelic dilactone, cyclohexane-1,4-dione, and a mixture of decomposition products that include acetic acid, propionic acid, acrylic acid, acetaldeide, acrolein, oxalic acid, cyclopentanone, and furane. In argon atmosphere, thermal degradation of succinic anhydride takes place at 340°C (123). Electrolysis of succinic acid produces ethylene and acetylene. 

Recently Dhandraj and Guillet 21> reported a new photochemical synthesis of block copolymers by irradiation of poly(tetramethylene sebacate-CO-y-ketopimelate) in the presence of methyl methacrylate. The chain radicals formed from the Norrish Type I cleavage of the y-ketopimelate unit initiated polymerization of methyl methacrylate leading to blocks the length of which depend on the number of scissions. 

The reaction of a mercurio ketone and carbon monoxide in the presence of a palladium catalyst in methanol (Scheme 26) results in the formation of a 1,4-keto ester with incorporation of one molecule of carbon monoxide. Treatment of a mercurio ketone with [Ni(CO)4] results in symmetrical coupling with incorporation of one molecule of carbon monoxide to give a triketone, presumably via a 3-nickel-sub-stitut ketone (Scheme 27) Such symmetrical coupling reactions are general for alkylmercury compounds. If silyloxycyclopropane (8) is heated in CHCb in the presence of a catalytic amount of a palladium-phosphine complex under CO, symmetrical coupling with incorporation of one molecule of CO takes place to give a 4-ketopimelate (Scheme 27). ... 

Ahpiperidine-2,6-dicarboxylate dehydrogenase (Q) N-succinyl-2-amino-6-ketopimelate synthase succinyl diaminopimelate aminotransferase succinyl diaminopimelate desuccinylase diaminopimelate epimerase diaminopimelate decarboxylase (Q threonine dehydratase (serine dehydratase) acetolactate synthase acetohydroxy acid isomeroreductase dihydroxy acid dehydratase valine aminotransferase a-isopropylmalate synthase isopropylmalate isomerase -isopropylmalate dehydrogenase leucine aminotransferase... 

Coned. H2S04 added, in very small portions at first, with manual stirring at —20 to 5° to diethyl a- (m-methoxyphenylethyl) -/ -ketopimelate, then allowed to warm to near room temp., and worked up, whereby the ester is hydrolized by refluxing 2.5 hrs. in aq. ale. KOH — y-(6-methoxy-2-carboxy-3,4-dihydro-l-naphthyl)-butyric acid. Crude Y 82%. (J. H. Hunter and J. Al Hogg, Am. Soc. 71, 1922 (1949).) s. a. 2, 795... 

Fig. 12. Seasonal changes in the relative abundances of (a) oxalic acid, (b) malonic acid, (c) succinic acid, (d) glutaric acid, (e) adipic acid, (f) azelaic acid, (g) 4-ketopimelic acid, (h) malic acid, (i) phthalic acid, and (j) maleic (hydroxysuccinic) acid in the total aerosol carbon (TC) in the aerosol samples from Jeju Island.

Palladium is a useful catalyst in several reactions which lead to keto-esters. p-Keto-esters react with allylic carbonates, with catalysis by palladium, in a decarboxylative allylation reaction. y-Keto-esters are prepared, in reasonable yield, by the palladium-catalysed regioselective oxidation of Py-unsaturated esters. y-Keto-esters are obtained in good yield by the palladium-catalysed Reformatsky reaction of ethyl bromoacetate and acid chlorides. Derivatives of y-ketopimelic acid are formed by the rhodium-carbonyl-catalysed reaction of derivatives of acrylic acid with carbon monoxide. A mild method for the conversion of propiolic esters into P-keto-esters via thiol addition has been reported (Scheme 63) it has been used in a formal synthesis of ( )-thienamycin. 

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