Chromone derivatives

Morita, N. 1992. Chrysograyanone, a novel chromone derivative from Chrysosplenium grayanum Maxim. Tetrahedron Lett. 33 5977-5980. 

Method B involves the preparation of precursor of 2-alkyl-l-benzo-pyrylium salts, as shown in Scheme ll.50 2-Alkylbenzopyrylium salts have been prepared by condensation of salicylaldehyde with appropriate ketone in acetic acid or by alkylation or reduction of coumarin or chromone derivatives. Reaction of 2-alkylbenzopyrylium salts with salicylaldehyde gives directly a spirodibenzopyran or 2-vinynologue benzopyrylium salt 17 which then can be converted into the spirodibenzopyran by piperidine or pyridine. 

In order to study any chemoselectivity influences of microwave irradiation on the domino Knoevenagel/hetero-Diels-Alder process (the so-called Tietze reaction), Raghunathan and coworkers [31a] investigated the transformation of 4-hydroxy coumarins (10-85) with benzaldehydes 10-86 in EtOH to afford pyrano[2,3-c]cou-marin 10-87 and pyrano[2,3-b]chromone derivatives 10-88. Normal heating of 10-85a and 10-86a at reflux for 4h gave a 68 32 mixture of 10-87a and 10-88 in 57% yield, whereas under microwave irradiation a 97 7 mixture in 82% yield was obtained. Similar results were found using the benzo-annulated substrates 10-85b and 10-86b. 

In an alternative strategy functionalized phenols, such as iodophenol, were involved in palladium-catalyzed carbonylation of alkynes or allenes, producing coumarin or chromone derivatives (Scheme 23) [130-133]. After oxidative addition of the iodoarene to the Pd(0) catalyst the order of insertion of either CO or the unsaturated substrate mainly depends on the nature of the substrate. In fact, Alper et al. reported that CO insertion occurs prior to allene insertion leading to methylene- or vinyl-benzopyranone derivatives [130]. On the contrary, insertion of alkynes precedes insertion of CO, affording couma-rine derivatives, as reported by Larock et al. According to the authors, this unusual selectivity can be explained by the inability of the acyl palladium species to further react with the alkyne, hence the decarbonylation step occurs preferentially [131-133]. 

Synthesis of 3-substituted chromone derivatives for their antibacterial studies. 

In contrast, the anodic fluorination Scheme 117. of Q , 8-unsaturated cyclic heterocycles The regioselective electrohalomethoxy-such as flavone [222] or thioflavone lation of chromone derivatives is followed... 

Khellin (32) Cromolyn sodium (33) Chromone derivative Vernal keratoconjunctivitis, vernal conjunctivitis, and vernal keratitis... 

Dicoumarol Dicoumarol, 3,3 -methylene-bis(4-hydroxycoumarin) (24.1.8), is synthesized from 4-hydroxycoumarine (24.1.7), which is in turn synthesized from salicylic acid methyl ester by cyclization to a chromone derivative using sodium or sodium methoxide or from o-oxyacetophenone by reacting it with diethylcarbonate in the presence of sodium ethoxide. Condensation of the resulting 4-hydroxycoumarin with formaldehyde as a phenol component gives dicoumarol [6-9],... 

The 1 1 adducts (300) formed in the reaction of phenols with DMAD have been successfully employed in the synthesis of several chromone derivatives (301) [Eq. (42)]. - i > An interesting case... 

Carbonyl stretching frequencies for pyran-2-one, pyran-4-one, coumarin, isocoumarin and chromone derived from the bond orders obtained using EHT agree well with the experimental data (78IJC(A)64). 

IR data are presented and analyzed in other reports of chromone derivatives (70JCS(C)2230, 70JCS(C)2609,74T3563) and in the monograph by Ellis <77HC(3i)i>. 

The moderate yield of cyclopalladated products could be increased using ligand exchange reactions starting from another cyclopalladated complex.131 Other thioketones such as thioxanthone, dithioxanthone, and thio-chromone derivatives react in a similar way, affording cyclopalladated compounds.132... 

Methylesculetol-6,7-dinicotinate (32) is useful as an antiinflammatory and vasodilator oflow toxicity (101). The synthesis of asarone [5555-15-1] (2,4,5-trimethoxy-l-propenylbenzene), which is used as a tranquilizer, has been patented (102). It occurs in calamus root, Acorns calamus L.y and is a chemosterilant for insects (103). 6,7-Dihydroxycoumarin-4-methylsulfonic acid and its salts are useful in the treatment of capillary permeability and fragility and for protecting oxidizable metabolites and drugs against biooxidation (104). Certain chromones derived from hydroxyhydroquinone, eg (33), and its salts, esters, and amides are valuable in the prophylactic treatment of asthma (105) (see Antiasthmatic agents). 2-Methoxy-6-multiprenyl-l,4-benzoquinones are intermediates in the microbiological synthesis of coenzyme Q compounds (106). 

Triflic acid supported on titania has proved to be an effective catalyst to transform hydroxyphenyl-l,3-propanediones to chromone derivatives in high yield and with high selectivity690 [Eq. (5.246)]. 

Yagura T, Ito M, Kiuchi F, Honda G, Shimada Y (2003) Four New 2-(2-Phenylethyl) chromone Derivatives from Withered Wood of Aquilaria sinensis. Chem Pharm Bull 51 560... 

A copper(ll)-catalyzed cyclopropanation of the chromone derived benzylium triflates 1110 with the diazoester 1111 affords 2,3-cyclopropyl chroman-4-ones 1112 in good yield (Scheme 276) <2005TL4057>. 

The chromones (4H-1 -bcnzopyran-4-oncs) have attracted attention from the viewpoint of both biological activity [41,42] and organic synthesis [42,43]. Chromone derivatives have been found to exhibit a broad range of biolog-... 

The 6-substituted 3-formylchromone derivatives (FC1-8) screened for their tumor-specific cytotoxic potentials are shown in Fig. 7. Their CC50 values for the four tumor cell fines and three normal cells are summarized in Table 3. Cytotoxic data for the related chromone derivatives (FC9-13),... 

Eiden, F. and Herdeis, C., Chromon-derivate aus Mannich-basen, Arch. Pharm, 310, 573, 1977. 

Extensive studies by Brov/n continue to elucidate the pathways to the furanocoumarins in various plants. Marmesin (13) and columbianetin (14) are still the only coumarin precursors of the furanocoumarins to retain a whole iso-prenoid unit. The related chromone derivative visamminol (15) is presumably a precursor of the furanochromone visnagin. Full details have appeared on the specific incorporation of mevalonate into the furan ring of skimmi-anine (16). 

Rajanna, K. C., Solomon, F., Ali, M. M., Saiprakash, P. K. Kinetics and mechanism of Viismeier-Haack synthesis of 3-formyl chromones derived from o-hydroxy aryl alkyl ketones a structure reactivity study. Tetrahedron 1996, 52, 3669-3682. 

Chromone derivatives, in particular 2-spiro-chroman-4(lF/)-ones, are ubiquitous in nature and possess various biological activities which include antiarrhythmic, anti-HIV, antidiabetic, acetyl-CoA carboxylase (ACC) inhibitor, vanilloid receptor antagonist, growth hormone secretagogues, histamine receptor antagonist, and... 

Even though various antileukotriene drugs have been synthesized, none has reached clinical acceptability. Inhibition of histamine release by an apparent mast cell stabilizing mechanism (in lung tissue, but probably not elsewhere) is achieved with the carboxy-chromone derivative cromolyn sodium. The mechanism is believed to involve inhibition of histamine release from pulmonary mast cells by blocking Ca2+ movement through membrane channels. 

Although 5,7-dimethoxychromone (63) showed weak antidote activity against MBC (12) as described in PP. 472 and 473 (Fig. 7), another chromone derivative, 5-hydroxy-7-methoxychromone (64) synthesized in... 

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