Isocitric lactone

FIGURE 5.1. Crystal structure of potassium isocitric lactone, showing the direction of cleavage. Potassium ions large black circles, oxygen atoms small filled circles, carbon atoms open circles, hydrogen atoms omitted. K+ - 0 dotted lines, hydrogen bonds dashed lines. 

Figure 24 (a) ID 400 MHz H NMR spectrum of the nine-component mixture in CDC13. (1) DL-isocitric lactone, (2) (S)-(+)-0-acetylmandelic acid, (3) DL-iV-acetylho-mocysteine thiolactone, (4) ( + )-sec-butyl acetate, (5) propyl acetate (6) isopropyl butyrate, (7) ethyl butyryl acetate, (8) butyl levulinate, (9) hydroquinine-9-phenanthryl ether, (b) PFG ID H NMR spectrum of the mixture without hydroquinine-9-phe-nanthryl ether, (c) PFG ID H NMR spectrum of the nine component mixture using LED sequence. Chemical shifts arising from compounds 1 and 2 are shown. All other shifts are from compound 9. The PFG conditions were the same as in (b). 

A procedure for the slow and sustained release of the growth hormone inhibitor Lanreotide is described. The method entails incorporating Lanreotide to the isocitric acid lactone component on the backbone of a polyester block copolymer using sodium hydroxide as the saponification agent. 

Preparation of Poly(isocitric Acid Lactone-co-Propanediol)... 

A reactor containing a Dean-Stark trap was charged with isocitric acid lactone (14.3 mmol), propanediol (15.7 mmol), and benzene was then refluxed at 90°C overnight. The mixture was concentrated and a viscous liquid isolated that solidified on cooling. 

Preparation of Poly[(Isocitric Acid Lactone-co-Propanediol)-fe/oc -(Glycolide-co-Lactide)]... 

Glusker, J. P., Patterson, A. L., Love, W. E., and Dornberg, M. L. X-ray crystal analysis of the substrates of aconitase. IV. The configuration of the naturally occurring isocitric acid as determined from potassium and rubidium salts of its lactone. Acta Cryst. 16, 1102-1107 (1963). 

CJ-15,183 (44) has been isolated from the fermentation culture of the fungus, Aspergillus aculeatus CL38916 as a squalene synthase inhibitor. The compound potently inhibited rat liver and human squalene synthases. In addition, it showed antifungal activities against filamentous fungi and yeast. The structure was elucidated to be an aliphatic tetracarboxylic acid compound consisting of an alkyl y-lactone, malic acid and isocitric acid moieties by spectroscopic analyses [69]. 

The synthesis of ( + )-isocitric acid lactone (255) is accomplished in 5 steps starting from the (25, 3 )-allyl malate 225d, as shown in Scheme 34 [86]. The key step in the sequence is oxidation of the allyl function with periodate and then permanganate to a carboxylate (251 252), which occurs in quantitative yield. Once the carbon framework is in place, all... 

A short synthesis of ( —)-isocitric acid (956) relies on alkylation of malic acid to introduce the requisite acetic acid functionality (Scheme 140) [208]. Alkylation of the dianion of dimethyl (T )-malate with trimethylsilylpropargyl bromide gives 953 in 51% yield as a 10 1 mixture of diastereomers. The mixture is separable by column chromatography after conversion to acetate 954. Oxidation of the acetylene to an acid followed by esterification furnishes the triester 955, which upon acid hydrolysis gives the lactone 956. 

Scheme 19.11 Lactone formations from tiimethyl isocitrate. Reagents and conditions a) toluene, pTsOH (cat.), reflux (Dean-Stark) b) HCl (4 M), reflux...

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