Plant coumarins: V. Palladium-catalyzed amination of 2-(1,3-dibromopropan-2-ylidene)oreoselone

Palladium-catalyzed amination of 2-(1,3-dibromopropan-2-ylidene)-7H-furo[3,2-g]chromene-3,7(2H)-dione with various amines and amino acid derivatives led to the formation of the corresponding 2-(1,3-diaminopropan-2-ylidene)-substituted oreoselones. The yields depended on the catalytic system, base, and amine structure. Di- and polyazamacrocyclic furocoumarin derivatives were obtained by reactions of 2-(1,3-dibromopropan-2-ylidene)-7H-furo[3,2-g]chromene-3,7(2H)-dione with linear di- and polyamines (hexamethylenediamine, spermine, spermidine, and 3,6-dithiaoctane-1,8-diamine), catalyzed by palladium complexes.     

A convenient synthesis of furo[3,2-c]pyran-3-carboxylates from 3-bromo-3-nitroacrylates

Novel 4-oxo-4H-furo[3,2-c]pyran-3-carboxylates and 4-oxo- 4H-furo[3,2-c]chromene-3-carboxylates were prepared from available alkyl 3-bromo-3-nitroacrylates and 4-hydroxy-6- methyl-2H-pyran-2-one or 4-hydroxycoumarin, respectively. Their structures were confirmed by NMR and X-ray data.     

Facile ionic liquid-mediated,three-component sequential reactions for the green,regio- and diastereoselective synthesis of furocoumarins

An environmentally friendly approach to the diastereoselective synthesis of trans-4-oxo-3-aryl-3,4-dihydro-2H-furo[3,2-c]coumarin-2-carbonitriles, trans-2-benzoyl-3-(aryl)-2H-furo[3,2-c]chromen-4(3H)-ones and trans-ethyl-4-oxo-3-(aryl)-3,4-dihydro-2H-furo[3,2-c]chromene-2-carboxylates in good yields is described. The method is based on the sequential multicomponent reactions of 4-hydroxycoumarin, aromatic aldehydes and in situ generated cyanomethylpyridinium, phenacylpyridinium/(2-ethoxy-2-oxoethyl)pyridinium ylides, in the presence of the ionic liquid [BMIm]OH, which functions both as a catalyst and the reaction medium.     

Reaction of 4-hydroxycoumarin with 2-acetyloxiranes

The reaction of 4-hydroxycoumarin with 2-acetyloxiranes in dimethylformamide in the presence of triethylamine gave 2,3-dihydro-4H-furo[3,2-c]chromen-4-ones which were converted into 4H-furo[3,2-c]-chromen-4-one derivatives as a result of dehydration or fragmentation.     

Synthesis and antimicrobial evaluation of the novel heteroannulated furo[3′,2′:6,7]chromeno[2,3-b]pyridines: Part 1

The chemical behavior of 4,9-dimethoxy-5-oxo-5H-furo[3,2-g]chromene-6-carbonitrile ( 1 ) was investigated toward some acyclic and cyclic active methylene ketones namely acetylacetone, ethyl acetoacetate, ethyl benzoylacetate, acetoacetanilide, dimedone, indanedione, pyrazolidine-3,5-dione and 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, barbituric acid and 1-allylthiobarbituric acid, and hippuric acid. A variety of novel heteroannulated furochromenopyridines were efficiently synthesized through a cascade reactions between 4,9-dimethoxy-5-oxo-5H-furo[3,2-g]chromene-6-carbonitrile ( 1 ) and the carbon nucleophilic reagents. Structures of the new products were inferred based on their analytical and spectral data.     

Synthesis of thio- and furan-fused heterocycles: furopyranone,furopyrrolone, and thienopyrrolone derivatives

We report herein the synthesis of a novel class of compounds, ethyl 4-oxo-4H-furo[3,2-c]pyran-6-yl carbonate, (7E)-7-[(dimethylamino)methylene]-4H-furo[3,2-c]pyran-4,6(7H)-dione, 5-oxo-N-phenyl-2,5-dihydro-4H-furo[3,2-b]pyrrole-4-carboxamide, and 5-oxo-N-phenyl-5,6-dihydro-4H-thieno[3,2-b]pyrrole-4-carboxamide starting from the corresponding acid derivatives. Intramolecular cyclization in the presence of thionyl chloride formed the target fused ring systems. Additional transformation was seen in the cyclization of furan-fused heterocycle. A mechanism was proposed based on experimental and computational findings.     

Ag2Cr2O7 nanoparticles: An eco-friendly and reusable catalyst for synthesis of pyrano[c]chromenediones and [1,3]dioxolo[g]chromeneones in aqueous media at ambient temperature

An efficient and green protocol for the synthesis of 4-aryl-3,4-dihydro-2H,5H-pyrano[3,2-c]chromene-2,5-diones and 8-aryl-7,8-dihydro-6H-[1,3]dioxolo[4,5-g]chromene-6-ones through the Ag₂Cr₂O₇ nanoparticles catalyzed cyclocondensation reaction of active methylene compounds including 4-hydroxycoumarin or 3,4-methylenedioxyphenol, aromatic aldehydes, and meldrum's acid in water at ambient temperature was described. This method demonstrates several advantages compared with methods that are currently employed such as a mild reaction conditions, simple work-up, good to excellent yields, avoiding toxic catalyst and hazardous solvent, and recovery and reuse of the catalyst.     

A metal-free C–C/C–O bond formation for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide catalyzed by polystyrene-supported p-toluenesulfonic acid (PS-PTSA)

An efficient and eco-friendly procedure for the synthesis of 2-amino-5-oxo-4-aryl-4H,5H-pyrano[3,2-c]chromene-3-carboxamide has been developed through a one-pot three-component condensation of 4-hydroxycoumarin with aldehydes and cyanoacetamide, in the presence of catalytic amount of polystyrene-supported p-toluenesulfonic acid (PS-PTSA) as a highly active and reusable heterogeneous acid catalyst in EtOH at 80?°C conditions. This new procedure offers several advantages such as shorter reaction times, excellent yields, a wide range of functional group tolerance, easy experimental work-up procedure, operationally simple under metal-free reaction conditions and C-C/C-O bond formation. The catalyst can be recovered and reused for at least four runs without any significant impact on the product yields.     

Synthesis of novel pyrano fused quinolones,coumarins, and pyridones

Dedicated to Professor Dr. Hans Junek, Graz, on the occasion of his 70th birthday A novel efficient synthesis of pyrano fused heterocycles namely, pyrano[3,2-c]quinoline-2,5(6H)-diones 3a-e, 7b-d , pyrano[3,2-c]benzopyran-2,5(6H)-dione ( 7f ), and pyrano[3,2-c]pyridine-2,5(6H)-diones 10, 11 was achieved by the condensation of 4-hydroxy-2-(1H)-quinolones 1a-e , 4-hydroxycoumarin ( 1f ), or 4-hydroxy-2(1H)-pyridone ( 9 ) with α-acetyl-γ-butyrolactone ( 2 ) or the sodium salt of α-formyl-γ-butyrol-actone ( 6 ), respectively, in the presence of ammonium acetate.     

Efficient synthesis of chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives via multicomponent one-pot reaction under mild reaction conditions in water

10-Methyl-7-aryl-7,12-dihydro-6H,8H-chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives are significant class of compounds and this is critical to develop methods in water using commercially available and non-toxic catalysts. In this paper, an efficient method is introduced for the synthesis of 10-methyl-7-aryl-7,12-dihydro-6H,8H-chromeno[4,3-b]pyrano[3,4-e]pyridine-6,8-dione derivatives. For the synthesis of the desired products, a multicomponent reaction was designed and performed between 4-hydroxycoumarin, an aldehyde, 6-methyl-2H-pyran-2,4(3H)-dione, and ammonium acetate. The products are obtained under green conditions in water in the presence of a catalytic amount of L-proline (10 mol%). The advantage of this method is no need to any toxic solvent, which is critical from the environmental viewpoint. A possible mechanism was suggested, which confirms the role of L-proline in the reaction as the catalyst.

     

Highly regio- and diastereoselective three-component reaction of acyclic/cyclic donor–acceptor carbenoids for the synthesis of angularly fused furocoumarins and spirooxindolylfurocoumarins

A highly regio- and stereoselective method has been developed for the synthesis of spiro[furo[3,4-c]chromene-1,3′-indoline]-2′,4(9bH)-dione derivatives via a three component reaction of cyclic diazoamide and aldehyde with methyl 2-oxo-2H-chromene-3-carboxylate, 3-acetyl-2H-chromen-2-one and 3-benzoyl-2H-chromen-2-one using 3 mol % of Rh₂(OAc)₄. Similarly, acyclic diazoesters also undergo smooth coupling with carbonyl compounds and 3-substituted coumarin in the presence of 1 mol % of Rh₂(OAc)₄ to afford a novel series of tetrahydro-1H-furo[3,4-c]chromene-1-carboxylates in 78–88% yield with high regio- and stereo-selectivity for the first time.     

2,2′-Bifurylidene-5,5′-diones,Coumarins, 3a, 7a-dihydro-1H-inden-1-ones,and 5H-furo[3,2-b]pyran-5-ones from propyne and carbon monoxide

The [Co₂ (CO)₈]-catalyzed reaction between propyne and CO in acetone at 110° and 170 bar was re-investigated. There are five major products: (E)-3,4′-dimethyl-2,2′-bifurylidene-5,5′-dione ( 4 ), 3,5,8-trimethylcoumarin ( 8 ), 3a, 7a-dihydro-2,4,7,7a-tetramethyl-1H-inden-1-one ( 9 ), 2,6-dimethyl-5H-furo [3,2, -b]- pyran-5-one ( 11 ), and 2,7-dimethyl-5H-furo 3,2-b-pyran-5-one ( 12 ); of these, only one, 4 . had previously been recognized. In parallel experiments were obtained 2,6-dipentyl-5 H-furo[3,2-b]pyran-5-one ( 13 ), 2,7-dipentyl–5H-furo[3,2-b]pyran-5-one ( 14 ), 3a, 7a-dihydro-2,4,7,7a-tetrapentyl-1H-inden-1-one ( 15 ). And 3a, 7a-dihydro-2,4,6,7a-tetrapentyl-1H-inden-1-one ( 16 ) from hept-1-yne, and two further types of products from two atypical 1-alkynes: 3,6,9-tri(tert-butyl)-1-oxaspiro[4.4]nona-3,6,8-trien-2-one ( 20 ) from (tert-butyl)acetylene and the exo-dimer 21 of 2,5-bis(trimethylsilyl)cyclopenta-2,4-dien-1-one ( 22 ) from (trimethylsilyl)acetylene. Compounds 11,12 , and 20 were identified by X-ray analysis.     

Synthesis of novel 4<Emphasis Type="Italic">H</Emphasis>-furo[3,2-c]pyran-4-ones and 4<Emphasis Type="Italic">H</Emphasis>-furo[3,2-<Emphasis Type="Italic">c</Emphasis>]chromen-4-ones

It was found that the condensation of two equivalents of 4-hydroxy-6-methyl-2H-pyran-2-one or 4-hydroxycoumarin with arylglyoxals in boiling formic acid leads to 4H-furo[3,2-c]-pyran-4-ones or 4H-furo[3,2-c]chromen-4-ones, respectively.     

Synthesis of derivatives of pyrido[3′,2′:4,5]furo[3,2-c]isoquinoline heterocyclic system

An approach to the synthesis of derivatives of new heterocyclic system, pyrido[3′,2′:4,5]-furo[3,2-c]isoquinoline, was suggested. A condensation reaction of substituted 3-cyanopyridin-2(1H)-ones with methyl 2-(chloromethyl)benzoate and subsequent treatment of the condensation product with potassium tert-butoxide leads to substituted pyrido[3′,2′:4,5]furo[3,2-c]-isoquinolin-5(6H)-ones. Similarly, a condensation reaction of substituted 3-cyanopyridin-2(1H)-ones with 2-(chloromethyl)benzonitrile and subsequent treatment of the condensation product with potassium tert-butoxide gives substituted 5-aminopyrido[3′,2′:4,5]furo[3,2-c]-isoquinolines.     

Intramolecular cyclization of ketene containing both acyl andN-alkylimidoyl substituents. Synthesis and crystal and molecular structure of 3-benzoyl-5-phenyl-2H,4H-furo[3,2-c] isoquinolin-2-one

Thermal decarbonylation of 1-benzyl-4,5-dibenzoyl-2,3-dihydropyrrole-2,3-dione yields benzoyl[N-benzyl(phenylglyoxalimidoyl)]ketene. The latter undergoes intramolecular cyclization to 3-benzoyl-5-phenyl-2,3,4,5-tetrahydrofuro[3,2-c]isoquinolin-2-one. Which is oxidized to 3-benzoyl-5-phenyl-2H,4H-furo[3,2-c]isoquinolin-2-one under the reaction conditions. The crystal and molecular structure of the title compound was studied by X-ray structural analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 563–565, March, 1997.     

Electrocatalytic multicomponent assembling of aldehydes, 4-hydroxycoumarin and malononitrile: An efficient approach to 2-amino-5-oxo-4,5-dihydropyrano(3,2-c)chromene-3-carbonitrile derivatives

2-Amino-5-oxo-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile derivatives are obtained in excellent yields by a simple, mild and efficient procedure by an electrocatalytic multicomponent chain transformation of aryl aldehydes, 4-hydroxycoumarin and malononitrile under neutral and mild conditions by electrolysis in an undivided cell in the presence of sodium bromide as an electrolyte.     

An efficient synthesis of spiroacridinone derivatives from the facile reaction of isatins,dimedone, and 5-aminoindazole (6-aminoindazole or 5-aminoindole)

We have developed a simple and facil protocol for the synthesis of tetrahydrospiro(indoline-3,11′-pyrazolo[4,3-a]acridine)-2,10′(7′H)-dione, tetrahydrospiro(indoline-3, 11′-pyrazolo[3,4-a]acridine)-2,10′(7′H)-dione, and tetrahydrospiro (indoline-3,11′-pyrrolo[3,2-a]acridine)-2,10′(7′H)-dione via PTSA·H₂O-induced cyclization reaction from isatins, dimedone, and 5-aminoindazole (6-aminoindazole or 5-aminoindole) in mixed solvent (EtOH and CH₃CN). In this research, 5-aminoindazole, 6-aminoindazole, and 5-aminoindole were effectively used to react with isatins and dimedone to give spiroacridinone derivatives. The advantages of this method are mild conditions, convenient manipulation, high yields, and a wide range of substrates.     

The synthesis of methyl 2-(benzyloxycarbonyl)amino-3-dimethylaminopropenoate. The synthesis of trisubstituted pyrroles, 3-amino-2H-pyran-2-ones,fused 2H-pyran-2-ones and 4H-pyridin-4-ones

Methyl 2-(benzyloxycarbonyl)aimno-3-dimemylaminopropenoate ( 2 ) was prepared from methyl N-(benzyloxycarbonyl)glycinate ( 1 ) and t-butoxybis(dimethylamino)methane, and used as a reagent for preparation of substituted 3-(benzyloxycarbonyl)amino-4H-quinolizin-4-ones 5 and 6 , ?2H-pyran-2-ones 17–19 , ?2H-1-benzopyran-2-ones 28–31 , and -naphthopyrans 32–35 , ?2H-pyrano[3,2-c]pyridine-2,5-dione 46 , -pyrano-[4,3-b]pyran-2,5-dione 47 , -pyrano[3,2-c]benzopyran-2,5-dione 48 , -pyrano[2,3-c]pyrazol-6-ones 49 and 50 , -pyrano[2,3-d]pyrirnidin-7-ones 51 and 52 derivatives. In the reaction of 2 with 1,3-diketones trisubsti tuted pyrroles 14–16 were formed. Selective removal of benzyloxycarbonyl group was achieved by cat alytic transfer hydrogenation with Pd/C in the presence of cyclohexene to afford free 3-amino compounds 7 , 8 , 20 , 36–38 and 53–57 in yields better than 80%.     

Application of N,3-diaryl-3-oxo-propanethioamide in synthesis: an efficient and mild domino approach to highly substituted fused chromenones

A convenient and rapid synthesis of hitherto unknown 3-aroyl-4-aryl-2-phenylamino-4H-benzo[g]chromene-5,10-diones in high yield from β-aroyl-thioacetanilide, aromatic aldehyde, and 2-hydroxy-1,4-naphthoquinone via InCl₃ catalyzed one-pot three-component tandem Knoevenagel condensation–Michael addition–intramolecular cyclization–elimination reaction sequence is disclosed for the first time. This domino protocol has been used to obtain highly substituted pyrano[3,2-c]chromen-5(4H)-ones and 7,7-dimethyl-7,8-dihydro-4H-chromen-5(6H)-ones from N,3-diaryl-3-oxo-propanethioamide, aromatic aldehyde, and 4-hydroxycoumarine or dimedone under mild reaction conditions. A plausible reaction mechanism is proposed. The 4H-pyrano[3,2-c]chromen-5-one and 7,7-dimethyl-7,8-dihydro-4H-chromen-5(6H)-one derivatives possessing 3-(2-chlorobenzoyl)-2-phenylamino-substituents further cyclized under basic conditions to yield penta-cyclic 7,13-diaryl-5,14-dioxa-13-aza-benzo[a]naphthacen-6,8(7H,13H)-dione and tetra-cyclic 6,12-diaryl-3,3-dimethyl-3,4-dihydro-2H-chromeno[2,3-b]quinolin-1,11(6H,12H)-dione, respectively.     

Convenient synthesis of linear 2H,6H-pyrano[3,2-g] chromenes from natural occurring compound; visnagin

Abstract

A simple and convenient rout for the synthesis of linear 2-imino-2H,6H-pyrano[3,2-g] chromen-6-ones and 2H,6H-pyrano[3,2-g]chromene-2,6-diones has been described starting from natural occurring furochromone; visnagin (1). Ring opening of 1 yielded 6-formyl-7-hydroxy-5-methoxy-2-methylchromone (2), which underwent reaction with different acetonitrile derivatives furnished 2-imino-2H,6H-pyrano[3,2-g] chromen-6-ones (5a–h). Acid hydrolysis of 5a–h led to the formation of 2H,6H-pyrano[3,2-g]chromene-2,6-diones (6a–h). Structures of the synthesized compounds were clarified based on their elemental analyses and spectral data. The entire target compounds were selected for in vitro anticancer activity against 60 human cancer cell lines at a single dose (10^?5 M) by the National Cancer Institute (NCI, Bethesda, USA).