4H-Chromon

H,10H-< 1-Benzopy rano[3,2-c] pyran) 3-Ethoxy-10-oxo-8-subst.-4,4a-dihydro- E14a/1, 420 (Enol-ether + 3-CHO —4H-chromon)... 

H-Chromon 3-Formyl-6-nitro-El6d, 286 (Nitrierung) Cyclobuten 3,4-Dioxo-2-hydroxy-1-(4-nitro-phenyl)- E15/2, 1432 (H - Ar)... 

Dimethyl-5,5 -dioxo- VI/2, 666 4H-Chromon 3-Hydroxy-7-methoxy-VI/4, 313 Cumarin... 

Amino-5-(2-hydroxy-benzoyl)-E9b/2, 170f. [2-(CO-NH2) 4H-chromon + Guanidin] 2-Benzyl-5-nitro- E9b/1, 33 [0HC-CH(N02)-CH0 + Ar—acetamidine] Pyrimido l,6-a]benzimidazol ... 

H-Chromon 2-Diazomethyl-5,7-dimethyl- E14b, 1028 (Sulfonyl-hydrazon/NaOH) Cyclobuta b quinoxalin 3,8-Dimethyl-1,2-dioxo-1,2,3,8-tetrahydro- E15/2, 1521 (NH - N-CH3)... 

Pyrimidin 5-(2-Hydroxy-benzoyl)-2-methyl- E9b/2, 170f. (3-CHO 4H-chromon + Acetamidin) Quinazolin 2-(2-Furyl)-4-methyl- -3-oxid E9b/2, 18 [2-(NH-CO-Het) —Ar— 1-CR = N —OH/H+] Quinolin 3-Amino-4-hydroxy-2-oxo-1 -(2-propinyl)-l, 2-dihydro-E15/2, 1251 (1,3-Oxazol-Spalt.)... 

Chlor-benzoyl)-2-pyrrolidino- 136 5-(4-Chlor-bcnzylidenamino)-2-(4-chlor-phenyl)-4-mercapto- -Piperidinium-Salz aus Dithiooxalsaure-diamid/4-Chlor-benzaldehyd/Piperidin 6 5-[4-(4-Chlor-bcnzyloxy)-phenyl]-2,4-dihydro xy-aus Chlor-[4-(4-chlor-benzyloxy)-phenyl]-acetonitril/Thioharnstoff 102 Chlorcarbonyl- 318 2-Chlor-5-chlormcthyl- 128 2-Chlor-4-(6-chlor-2-mcthyl-4H-chromon-... 

CH3 4,9 -Dimethoxy -5-oxo - 7-methyl-2,3,6,7-tetra-hydro -5H- (furo [g]-chromen) 56% d.Th. och3 och3 7-Hydroxy-5,8 -dimethoxy 2 -methyl-6-dthyl-4H -chromon 39% d.Th. 

Shelke et al. [80] S5mthesized various fluorine-containing compounds by conventional and nonconventional procedures by ultrasonication and microwave techniques. Various 3-substituted-l-phenyl-lH-pyrazole-4-carbaldehydes were treated with 3-(trifluoromethyl)-l-phenyl-lH-pyrazol-5(4H)-one (83) to give 4-((3-(4-aryl)-l-phenyl-lH-pyrazol-4-yl) methylene)-3-(trifluoromethyl)-l-phenyl-lH-pyrazol-5(4H)-one (85). Equivalent mole of 3-formylchromone and 3-(trifluoromethyl)-l-phenyl-lH-pyrazol-5(4H)-one by conventional method and nonconventional methods gave 3-(trifluoromethyl)-4-(4-oxo-4H chromon-3-yl)-methylene-l-phenyl-lH-pyrazol-(4H)-one (84) (Scheme 21). Compounds 84 and 85 were obtained in slightly better yields within 5-10 min under ultrasonication than in 2-3 min with microwave irradiation. 

H-l-Benzopyran-4-ones — see Chromones 4H-l-Benzopyran-4-ones, 2-phenyl — see Flavones Benzopyranopyrazoles synthesis, S, 317, 341 Benzopyrano[4,3-c]pytazol-4-one synthesis, 3, 712 Benzopyrano[4,3-6]pyridine synthesis, 3, 712 Benzopyrano[4,3-ii]pyrimidine synthesis, 3, 712 Benzopyrans nomenclature, 1, 23 pyrylium salt synthesis from, 3, 873 reactions... 

Pyran-4-one, 2,2,5-trimethyl-2,3-dihydro-photodimerization, 3, 720 4H-Pyran-4-one, 2,3-dihydro-2,3,5-trimethyl-6-( 1 -methyl-2-oxobutyl)-synthesis, 3, 844 Pyranones alkylation, 2, 56 aromaticity, 3, 632, 633 C NMR, 3, 587, 635 H NMR, 3, 580 cardiac glycosides, 3, 883 chromone synthesis from, 3, 830 colour couplers... 

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 contrast to the benzoannelated nitrogen heterocycles, only a few kinds of benzoannelated systems without nitrogen have been described (Fig. 3.15). Five-mem-bered rings such as benzo[b]furans (336) [184, 461] and hydrobenzo[b]furans (337) (Scheme 3.41) [337, 462, 463] and six-membered rings like 4H-l-benzopyran-4-ones (4-chromones) (338) and 2H-l-benzopyran-2-ones (coumarines) (339) [96, 464, 465] 2,3-dihydro-4H-l-benzopyran-4-ones (chroman-4-ones) (340) [466] and 3,4-dihydro-lH-2-benzopyrans (isochromans) (341) [444] have been reported. 

Chloroquinolines are reactive groupings due to electron-deficient carbon to which the halogen is attached. This carbon is electron-deficient due to the combined electron-withdrawing effects of the chlorine substituent and the quinoline nitrogen. The electrophilic carbon is thus able to react readily with nucleophiles present in the body. The impact of this grouping on a molecule is illustrated by 6-chloro-4-oxo-10-propyl-4H-pyrano[3,2-g]quinoline-2,8-dicarboxylate (Figure 8.28). In contrast to many related compounds (chromone-carboxylates) lacking the chloroquinoline, 6-chloro-4-oxo-10-propyl-4H-pyrano[3,2-g]quinoline-2,8-dicarboxylate is excreted as a... 

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-... 

Gaplovsky, A., Donovalova, J., Lacova, M., Mracnova, R., and El-Shaaer, H.M. 2000. The photochemical behaviour of 6-X-4H-3(bicyclo[2.2.1]-5-heptene-2,3-dicarboximidoimi-nomethyl)-4-chromones. Fhotochromism and thermochromism. Journal of Photochemistry Photobiology A Chemistry, 136 61-65. 

The chromones (4H-l-benzopyran-4-ones) have been reported to exhibit antifungal, antiviral, antimicrobial, antiallergic, antitublin, and antitumor activ-... 

As an initial step to the introduction of a carbonyl group at the 3-position of the chromone ring, we started with the synthesis of 3-formyl derivatives on which only a few reports (7., had been published. The 4-oxo-4H-l-... 

The final target, 3-(IH-tetrazol-5-yl)chromones (5), were synthesized by the reaction of sodium azide in the presence of anhydrous aluminum chloride and 4-OXO-4H-1-benzopyran-3 -carbonitri les ( ) which were obtained in one step from with hydroxylamine (22, 2 ) (Figure 2). 

Table I. Relative Potencies against Rat Passive Cutaneous Anaphylaxis (PCA) of 3-(IH-Tetrazo1-5-yl)-chromones i 3-( -Oxo-4H-l-benzopyran-3)-acrylic Acids (4), and DSCG...

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