7-PYRONE-2,6-DICARBOXYLIC ACID

Opium.—If opium is subjected to the action of the electric current the acid goes to the cathode and the base to the anode. Thus meconic acid (oxy-pyrone-dicarboxylic acid) was found at the positive pole and morphine (C H NO(OH)a) at the negative pole. 

Chelidonic acid, y-pyrone-dicarboxylic acid, C7H4O6,... 

Kersten PJ, S Dagley, JW Whittaker, DM Arciero, ID Lipscomb (1982) 2-Pyrone-4,6-dicarboxylic acid, a catabolite of gallic acids in Pseudomonas species. J Bacteriol 152 1154-1162. 

Meconic acid (3-hydroxy-Y-pyrone-2,6-dicarboxylic acid) [497-59-6] M 200.1, m 100 (-H2O). Crystd from water and dried at 100° for 20min. 

Several methods are available for the assembly of tricarbonyl precursors the synthesis of chehdonic acid (4-pyrone-2,6-dicarboxylic acid) represents the obvious approach of bringing about two Claisen condensations, one on each side of a ketone carbonyl group. Chelidonic acid can be decarboxylated to produce... 

ABSTRACT The review covers particularly the synthesis of fine chemicals via the formation of C-C bonds between carbon dioxide and hydrocarbons. In the reactions of CO2 with alkenes, dienes and alkynes a great number of carboxylic acids, dicarboxylic acids, esters, lactones and pyrones are formed, whether in stoichiometric or catalytic reactions. In each chapter the reactions are considered in the order of the transition metals applied. In addition, some syntheses will be mentioned which are closely related to transition metal catalysis, for instance the electrocarboxylation ofolefinic hydrocarbons. 

Other metabolites like 5,7-dihydroxy-8-methoxychroman-4-one (37) and possibly a coumarin derivative (35) have also been found in the bulb wax of E. comosa. From the bulb tissue of different Eucomis spp. a series of sterol derivatives, dibenzo-a-pyrones and a dicarboxylic acid have been isolated (69, 82). 

Acoxy-2-pyrone ring. 7-Nitrofluorene-l,9-dicarboxylic acid refluxed with acetyl chloride until after ca. 3 days the startg. m. has disappeared crude 9-nitro-l-acetoxy-2-oxa-3-oxo-2,3-dihydrofluoranthene. Y 89%. R. Kuhn and U. Breyer, B. 95, 111 (1962). 

The first synthesis of 4-pyrone derivatives with two CF3 groups was reported in 1988 by Lee and co-workers [22]. Acetone dicarboxylic acid monomethyl ester 47 reacted with isobutylene in sulfuric acid to form 48. Subsequent reaction with MgCL and trifluoroacetic anhydride led to pyrone 49. This compound was converted to the monoester 50, which gave pyrone 51. The latter was reacted with ammonia in methanol to form 4-hydroxypyridine 52 [22] (Scheme 15). 

Fused 3-bromo-5-carbethoxy-4,6-dimethyl-2-pyrone added rapidly to boiling 7 M KOH, the flask inclined at an angle of 40° to prevent loss during a violent evolution of alcohol occurring ca. 1 min. after the addition, then boiling continued for 30 min. frans-l-methylenecyclopropane-2,3-dicarboxylic acid. Y ... 

Hydroxy-4-pyrone-2,6 dicarboxylic acid. Meconic acid. 

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