Phenylmalonic acid

To a stirred suspension of p-(p-methoxvbenzyloxy)-phenylmalonic acid (125 mg) in methylene chloride (3 ml) are added triethylamine (55 All) and oxalyl chloride (26 AH) at -15°C, and the suspension is stirred for 40 minutes at 0°C. The mixture Is added to a solution of diphenylmethyl 7 -amino-7a-methoxy-3-(1 -methyltetrazol-5-yl)thiomethyl-1 -oxadethia-3-cephem-4methylene chloride (3 ml) and pyridine (63 AH), and the mixture is stirred for 30 minutes at 0°C. The reaction mixture is diluted with ethyl acetate, washed with aqueous 2 N-hydrochloric acid and water, dried over sodium sulfate, and concentrated to give crude product (212 mg), which Is chromatographed on silica gel (20 g) and... 

C,Hj04 2613-89-0) see Carfecillin Carindacillin phenylmalonic acid benzyl ester chloride (Ci Hi ClO 35353-13-0) see Carbenicillin phenylmalonic acid diethyl ester see under diethyl phenylmalonate phenylmcrcuric acetate... 

Although the absolute configurations of the products are opposite to that of antiinflammatory active compounds, and the substrate specificity is rather restricted as to the steric bulkiness around the reaction center, the enzyme system of A. bronchisepticus was proved to have a unique reactivity. Thus, detailed studies on the isolated enzyme were expected to elucidate some new interesting mechanism of the new type of decarboxylation. Thus, the enzyme was purified. (The enzyme is now registered as EC 4.1.1.76.) The molecular mass was about 24kDa. The enzyme was named as arylmalonate decarboxylase (AMDase), as the rate of the decarboxylation of phenylmalonic acid was faster than that of the a-methyl derivative. ... 

To clarify the characteristics of AMDase, the effects of some additives were examined using phenylmalonic acid as the representative substrate. The addihon of ATP and coenzyme A did not enhance the rate of the reaction, different from the case of malonyl-CoA decarboxylase and others in those, ATP and substrate acid form a mixed anhydride, which in turn reacts with coenzyme A to form a thiol ester of the substrate. In the present case, as both ATP and CoA-SH had no effect, the mechanism of the reaction will be totally different from the ordinary one described above. It is well estabhshed that avidin is a potent inhibitor of the formation of the biotin-enzyme complex. In the case of AMDase, addition of avidin has no influence on the enzyme activity, indicating that AMDase is not a biotin enzyme. 

To study the reaction mechanism, the electronic effect of the substituents (p-MeO, p-Me, p-C, m-Cl and H) on the rate of the reaction of phenylmalonic acid was examined. The logarithm of (H) cleanly correlated in a linear fashion... 

To screen a microorganism which has an ability to decarboxylate a-aryl-a-methylmalonic acids, a medium was used in which phenylmalonic acid was the sole source of carbon, because we assumed that the first step of the metabolic path would be decarboxylation of the acid to give phenylacetic acid, which would be further metabolized via oxidation at the a-position. Thus, a... 

To elucidate the metabolic pathway of phenylmalonic acid, the incubation broth of A. bronchisepticus on phenylmalonic acid was examined at the early stage of cultivation. After a one-day incubation period, phenylmalonic acid was recovered in 80% yield. It is worthy of note that the supposed intermediate, mandelic acid, was obtained in 1.4% yield, as shown in Eq. (8). The absolute configuration of this oxidation product was revealed to be S. After 2 days, no metabolite was recovered from the broth. It is highly probable that the intermediary mandelic acid is further oxidized via benzoylformic acid. As the isolated mandelic acid is optically active, the enzyme responsible for the oxidation of the acid is assumed to be S-specific. If this assumption is correct, the enzyme should leave the intact l -enantiomer behind when a racemic mixture of mandelic acid is subjected to the reaction. This expectation was nicely realized by adding the racemate of mandelic acid to a suspension of A. bronchisepticus after a 4-day incubation [4]. 

A. bronchisepticus was cultivated aerobically at 30 °C for 72 h in an inorganic medium (vide supra) in 1 liter of water (pH 7.2) containing 1 % of polypeptone and 0.5 % of phenylmalonic acid. The enzyme was formed intracellularly and induced only in the presence of phenylmalonic acid. All the procedures for the purification of the enzyme were performed below 5 °C. Potassium phosphate buffer of pH 7.0 with 0.1 mM EDTA and 5 mM of 2-mercaptoethanol was used thoughout the experiments. The enzyme activity was assayed by formation of pheylacetic acid from phenylmalonic acid. The summary of the purification procedure is shown in Table 2. The specific activity of the enzyme increased by 300-fold to 377 U/mg protein with a 15% yield from cell-free extract [9]. One unit was defined as the amount of enzyme which catalyzes the formation of 1 mmol of phenylacetic acid from phenylmalonic acid per min. 

We screened for a potent inhibitor against the AMDase-catalyzed decarboxylation of a-methyl-a-phenylmalonic acid to give a-phenylpropionic acid. Among the compounds shown in Fig. 4 which have structures similar to the substrate. 

In order to obtain more information on the reaction intermediate, the stereochemical course of the reaction was investigated. The absolute configuration of the product from a-methyl-a-phenylmalonic acid was unambiguously determined to be R, based on the sign of specific rotation. Then, which carboxyl group remains in the propionic acid and which is released as carbon dioxide To solve this problem we have to distinguish between two prochiral carboxyl... 

Fig. 8. Preparation and reaction of C-containing chiral a-methyl-a-phenylmalonic acid...

We examined the effect of restricted conformation on the activation entropy by kinetic studies at various temperatures [34]. Three kinds of substrates were subjected to the reaction phenylmalonic acid as the standard compound, ortho-chlorophenylmalonic acid as a substrate with an electron-withdrawing group, and indane-l,l-dicarboxylic acid as a conformationally restricted compound. The initial rates of the enzymatic decarboxylation reaction of three compounds were measured at several substrate concentrations at 15 °C, 25 °C, and 35 °C. The kcat and values at each temperature were obtained by a Lineweaver-Burk plot,... 

Carbenicillin Carbenicillin, [25 -(2a,5a,6j3)]-3,3-dimethyl-7-oxo-6-(2-carboxy-2-phenylacetamido)-4-thia-l-azabicyclo[3.2.0]-heptan-2-carboxylic acid (32.1.1.32), is synthesized by direct acylation of 6-APA in the presence of sodium bicarbonate by phenylmalonic acid monobenzyl ester chloride, which forms the benzyl ester of carbenicillin (32.1.1.31), the hydrogenolysis of which using palladium on carbon or calcium carbonate as catalyst gives the desired product (32.1.1.32) [51-58]. 

Phenylmalonic acid Benzyl alcohol Thionyl chloride 6-Amino penicillanic acid Hydrogen... 

The required monobenzyl phenylmalonate, MP 68°C, was prepared by treating a mixture of phenylmalonic acid (18 g) and benzyl alcohol (13 g) in carbon tetrachloride (80 ml) with dry hydrogen chloride. 

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