Chelidonic acid

Chelidonic acid has been found in many species of Amarylidaceae, Liliaceae, and also in Papaveraceae - particularly Chelidonium majus. It has been proposed that chelidonic acid is biosynthesized from 3-phospho-glyceric acid and a C4 unit such as erythrose-4-phosphate, which are products of the reductive photosynthetic pathway, in C. majus and Narcissus incomparibilis (69). It is clear that chelidonic acid is not derived from aromatic amino acids, from members of the TCA cycle, or from polyketide intermediates (49). 

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Natural chelidonic acid is obtained from the herb celandine Chelidonium majus). The synthesis from ethyl oxalate and acetone was first described by Claisen the process was simplified by Willstatter and Pummerer and further improved by Ruzicka and Fornasir.- The present procedure is modelled after that of the last-mentioned investigators. 

Citral Lemon grass oil, mandarin oil Chelidonic acid Asparagus, Celandine, anemone... 

Chelidonic acid has been found to exist in the free state in many plants (122). A concentration as high as 10 2 M, calculated on a fresh-weight basis, has been measured. Leopold et al. (89) found that chelidonic acid functioned as a growth inhibitor in the pea straight-growth test. Some inhibition was obtained at 10 5 M and 50% inhibition was measured at 10 4 M. Growth was promoted in the presence of IAA. This action is similar to that noted for coumarin and other unsaturated lactones. As with lactones, the inhibitory effect of chelidonic acid could be relieved by pretreatment of the tissue with BAL. 

The same product is obtained from 3-phenylchehdamic acid, the pyrone oxygen of which is already substituted by imino-nitrogen, only three molecules of biguanide being required for the formation of the final product (CXLVII). Similar reactions occur (464) with the parent chelidonic acid and with y-pyrone. 

Suggest a synthesis of chelidonic acid 4.9 from diethyl oxalate [(CO-fEt)2] and acetone (propanone). 

N.A. Veratrum viride Ait. Steroidal, alkaloids, chelidonic acid.99 Lower blood pressure, dilate the peripheral blood vessels. 

Chelidonic acid [6003-94-7] M 184.1, m 262 . Crystd from aqueous EtOH. 

Azinecarboxylic acids lose C02 significantly more easily than benzoic acid. Pyridinecarboxylic acids decarboxylate on heating with increasing ease in the order (3 < < y < a. 2-Pyridazinecarboxylic acid gives pyrazine at 200°C, and 4,5-pyrimidinedicarboxylic acid forms the 5-mono-acid on vacuum distillation. Pyrone- and pyridone-carboxylic acids also decarboxylate relatively easily thus, chelidonic acid (680 Z = O) at 160°C over copper powder and chelidamic acid (680 Z=NH) at 260°C give (681 Z = 0, NH). 

Decarboxylation is sometimes useful in structure investigations and in assignment of NMR signals. Chelidonic acid (488 R = H), which is widely distributed in plants, is doubly decarboxylated to pyran-4-one (487) on heating with copper powder. The monoester is decarboxylated to comanic acid ester (489). 

Oxopyran-2,6-dicarboxylic acid (chelidonic acid) is obtained from the base-catalyzed condensation of acetone with ethyl oxalate. The initial product is cyclized in acid... 

Chelidonic acid gantnia-pyi one-alpha, alpha-prime-dicarhoxylic add... 

Ceroplastol synthesis, 1, 428 Cetyl alcohol synthesis, 1, 478 Chaetoglobasins structures, 4, 376 Chalcone, a-azido-2 -oxy-synthesis, 3, 823 Chalcone, 2-hydroxy-reduction, 3, 751 Chalcone, 2 -hydroxy-mass spectra, 3, 618 Chalcone dibromides flavone synthesis from, 3, 823 Chalcones polymers, 1, 304 Chanoclavine synthesis, 6, 423 Charge density waves in stacks of ions, 1, 351-352 Chartreusin antibiotic, 3, 677 Chelating agents as pharmaceuticals, 1, 158-159 Chelating resins for metal ions, 1, 290 vinylimidazolecarboxylic acid as, 1, 281 Chelidonic acid — see Pyran-2,6-dicarboxylic acid, 4-oxo-... 

Sabina ketone (XXIV)26 and the esters of chelidonic acid (XXV)6 are reported not to be reduced by aluminum isopropoxide in boiling isopropyl alcohol solution. Apparently no attempts have been made to... 

Chelidamic acid 6.6B Chelidonic acid 6.6B Chelidonium Chelidostatin 13.5B Chenopodium RIP-I 9.1A Chicoric acid 9.5Ap Chlamydocin 9.6C Chloramphenicol 9.2n Chloro-dihydroillicinone E 6.1 A Chloro-dimethylaminopropyl-phenothiazine 5.4n... 

Synthesis of heterocycks. The synthesis of chelidonic acid from acetone, diethyl oxalate, and ethanolic sodium ethoxide, discovered by Claisen and perfected by Riegel and Zwilgmeyer, involves initially a double ester condensation to give acetonedioxalic ester as the sodio derivative. The free diester is liberated by neutralization and heated with hydrochloric acid to effect cyclization through the dienol and hydrolysis. 

Chelidonic acid (4-oxopyran-2,6-dicarboxylic acid) [99-32-1] M 184.1, m 262 , pK 2.36. The acid crystallises from aqueous EtOH. Dry it first at 100 /2hours, then at 160 to constant weight to remove water of crystallisation. It decarboxylates at 220-230° in a vacuum. [Riegel Zwilgmeyer Org Synth Coll Vol II 126 1943, Beilstein 18 H 490,18/8 V 646.]... 

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... 

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