Synthése par deux voies différentes d'un systéme dihétérocyclique apparenté aux peltogynoides

5-Oxo-5H,7H-[2]benzopyrano[4,3-b][1]benzopyran ( 2 ) has been synthesized from 3-(o-hydroxybenzylidene)isochroman-1,4-dione ( 3 ) by reductive cyclization, and from 5H,7H[2]benzo-pyrano[4,3-b][1]benzopyran-5,7-dione ( 4 ) by selective hydro-genation. This second method affords the dihydro compound 6 or 6a,12a-dihydro-5H,7H-[2]benzopyrano[4,3-b] [1 ]benzopyran-5-one as reaction time increases.     

Regioselective synthesis of 1H,3H,6H[2]benzopyrano[4,3-d]pyrimidine-2,4-diones and 12H-benzopyrano[3,2-c][1]benzopyran-5-ones by radical cyclization

5-Hydroxy uracils or 4-hydroxy[1]benzopyran-2-ones were refluxed with 2-bromobenzyl bromides in acetone in the presence of anhydrous potassium carbonate to afford a number of 5-(2′-bromobenzyloxy) pyrimidine-2,4-dione (80-92%) or 4-(2′-bromobenzyloxy) benzopyran-7-ones (70-82%) respectively. These were then refluxed with tri-n-butyltin chloride and sodium cyanoborohydride in the presence of a catalytic amount of azobisisobutyronitrile (AIBN) for 3-4 h to give 1H,3H,6H [2]benzopyrano[4,3-d]pyrimidine-2,4-diones (75-85%) or 12H-benzopyrano[3,2-c][1]benzopyran-5-ones (70-85%) respectively.     

Reactions of 4-Chloro-3-formylcoumarin with Arylhydrazines

The interaction of 3-formyl-4-coumarin with arylhydrazine hydrochlorides in the presence of sodium acetate gave the corresponding 3-arylhydrazonomethyl-4-chlorocoumarin, and with phenylhydrazine, 4-bromo- and 4-chlorophenylhydrazine hydrochlorides in the presence of two equivalents of triethylamine gave either 1-aryl- or 2-aryl[1]benzopyrano[4,3-c]pyrazol-4-ones depending on the reaction conditions. In reactions of 4-chloro-3-formylcoumarin with 2,4-dichloro-, 2,4-difluoro-, 2-hydroycarbonyl-, 4-nitro- and 3,5-di(trifluoromethyl)phenylhydrazine, 2-pyridyl- and 2-quinoxalylhydrazine in the presence of excess of triethylamine the 2-aryl[1]benzopyrano[4,3-c]pyrazol-4(2H)-ones were obtained exclusively. The structures of 1-phenyl- and 2-(2-pyridyl)[1]benzopyrano[4,3-c]pyrazolo-4(1H)ones were confirmed by X-ray crystallography. A simple method is proposed to distinguish between 1- and 2-substituted [1]benzopyrano[4,3-c]pyrazolo-4-ones on the basis of the ¹H NMR chemical shifts of the C(3)-H proton in two solvents - DMSO-d₆ and CDCl₃.     

Reaction of β-arylidennaphthylamines with 4-hydroxycoumarin. A correction in structural assignment of the product. III

The reaction of 4-hydroxycoumarin with β-arylidennaphthylamines constitutes a convenient synthetic route to the hitherto unknown 2H-benzo[f][1]benzopyrano[4,3-b]quinolin-2-one, VI . The X-ray crystallography data conform with the present benzopyrano[4,3-b]quinolin-2-one ring system and disprove the benzopyrano[3,4-c]quinolin-2-one structure previously assigned for such reaction products.     

3个新呋喃黄酮的NMR研究

从厚果难血藤（Millettia pachycarpa Benth)根中分离得到3个呋喃黄酮类化合物,经NMR谱等分析研究,确定了它们的结构为：4H－呋喃并[2,3-h][1]苯并吡喃－4－酮,3－甲氧基－2－（3,4,5－三甲氧基苯基）（I）、4H－呋喃并[2,3-h][1]苯并吡喃－4－酮,3－甲氧基－2（3－甲氧苯基）（Ⅱ）、10,11二甲氧基－[2]苯并吡喃[4,3-b]-呋喃并[2,3-h][1]苯并吡喃－6（8H）－酮（Ⅲ）,皆未见文献报道,分别命名为厚果鸡血藤丙素（pachycarin C)、厚果难血藤丁素（pachycarin D)和厚果鸡血藤戊素（pachycarin E)。     

Reaction of ketenes with N,N-disubstituted à-aminomethyleneketones. IX. Synthesis of 2H,5H-pyrano[3,2-c][1]benzopyran derivatives

Cycloaddition of dichloroketene to N,N-disubstituted 3-aminomethylene-4-chromanones gave in good yield N,N-disubstituted 4-amino-3,3-dichloro-3,4-dihydro-5H-pyrano[3,2-c][1]benzopyran-2-ones only in the case of aromatic N-substitution. Dehydrochlorination with triethylamine of these adducts afforded N,N-disubstituted 4-amino-3-chloro-5H-pyrano[3,2-c][1]benzopyran-2-ones in good to moderate yield. The cycloaddition to 3-dimethylaminomethylene-4-chromanone led directly to 3-chloro-4-dimethylamino-5H-pyrano[3,2-c][1]benzopyran-2-one.     

Mass spectrometric investigation of some [1]benzopyrano[3,4-c]pyrazole and [1]benzopyrano[4,3-d]isoxazole derivatives

The fragmentation behaviour of some [1]benzopyrano[3,4-c]pyrazole and [1]benzopyrano[4,3-d]isoxazole derivatives under electron impact is described.     

Unexpected behaviour of the oxidizing agent sodium m-nitrobenzenesulfonate: Synthesis of a new class of 5-hydroxy benzopyrano-[4,3-c]pyridazin-3(2H)-ones

Sodium m-nitrobenzene sulfonate, widely used in dehydrogenation of 4,5-dihydro-3(2H)-pyridazinones to their corresponding aromatic derivatives, behaves in an unexpected way when 4,4a-dihydro-5H[1]benzopyrano[4,3-c]pyridazin-3(2H)-ones are employed as substrate. The synthesis of a new class of 5-hydroxy[1]benzopyrano[4,3-c]pyridazin-3(2H)-ones is described.     

Structural reassignment of the dehydration product of 2′-Hydroxywarfarin

The base catalyzed condensation reaction between 4-hydroxycoumarin and o-hydroxybenzal-acetone yields 6-methyl-6,12-methano-6H,12H,13H-[1]benzopyran[4,3-d][1,3]benzodioxocin-13-one as the product rather than 6-oxo-7-(2-oxopropyl)-6H, 7H-[1]benzopyrano[4,3-b][1]-benzopyran as had been previously postulated.     

Synthesis of some N-heteroaromatic analogues of cannabinoids

The synthesis of some [1]benzopyrano[3,4-b]pyrazine, -[3,4-d]imidazole, -[4,3-c]imidazole, -[4,3-c]pyrazole and -[3,4-d]isoxazole analogues of cannabinoids is reported.     

New chromonocoumarin (=6H, 7H-[1]Benzopyrano[4,3-b][1]benzopyran-6,7-dione) derivatives from Polygala fruticosa BERG

Three chromonocoumarins ( =6H, 7H-[1]benzopyrano[4,3-b][1]benzopyran-6,7-diones) 1–3 have been isolated from the leaves and the root bark of polygala fruticosa BERG . (syn. Polygala oppositifolia L .; Polygalaceae). The structure of frutinone A ( 1 ) was established by X-ray diffraction analysis. The structures of the previously undescribed compounds frutinone B ( 2 ) and C ( 3 ) were deduced by spectroscopic methods (EI-MS, UV, IR, ¹H-and ¹³C-NMR, including NOE and COSY) in comparison with 1 . Chromonocoumarins 1–3 are the first representatives of a new type of naturally occurring compounds. Frutinone A shows strong fungicidal activity against Cladosporium cucumerinum.     

A comparison of electron impact mass spectrometry of isomeric pyranocoumarins (pyrano[3,2-c][1]benzopyran-5-ones) and pyranochromones (pyrano[2,3-b][1]benzopyran-5-ones)

The mass spectrometric behaviour of two pairs of isomeric 2,2-dimethylpyrano[3,2-c][1]benzopyran-5-ones (pyranocoumarins) and 2,2-dimethylpyrano[2,3-b][1]benzopyran-5-ones (pyranochromones) and four pairs of isomeric 2-hydroxymethyl-2-methylpyrano[3,2-c][1]benzopyran-5-ones (pyranocoumarins) and 2-hydroxymethyl-2-methylpyrano[2,3-b][1] benzopyran-5-ones (pyranochromones) has been studied in detail with the aid of exact mass measurements, linked scans, collisionally activated decompositions and deuterium labelling experiments. The presence in both series of compounds of the same ions derived by structural interconversion of both molecular ions is emphasized, and structural information on the ions [C₇H₅O₂]⁺ (m/z 121), highly characteristic for these classes of compounds, as for 4-hydroxycoumarins, is reported.     

Tetrahydropyran-2,4-diones in the Synthesis of Fused N,O-Heterocycles

Condensation of 6-methyl(or phenyl)-tetrahydropyran-2,4-diones with 2-aminonaphthalene or 6-aminoquinoline and aromatic aldehydes in an aliphatic alcohol gave 5-aryl-2,2-dimethyl(or 2-phenyl)-1,2,5,6-tetrahydro-4H-benzo[f]pyrano[3,4-c]quinolin-4-ones and 5-aryl-2-methyl-1,2,5,6-tetrahydro-4H-pyrano[4,3-a][4,7]phenanthrolin-4-ones which are new N,O-heterocyclic systems containing fused aza- and diazaphenanthrene moieties and a 2-pyranone ring.     

Synthesis of Precursors of Heterocyclic cis-β-Amino Alcohols by Intramolecular Amidoalkylation of 4-Hydroxyoxazolidin-2-ones

The reaction of intramolecular amidoalkylation of 4-hydroxyoxazolidin-2-ones leads to formation of novel and rare heterocyclic systems: substituted 1,5,6,10b-tetrahydro[1,3]oxazolo[4,3-a]isoquinolin-3-ones, 3a,4,5,10b-tetrahydro[1,3]dioxolo[4',5':6,7]naphtho[1,2-d][1,3]oxazol-2(1H)-ones, and 5,6,10,10a-tetrahydro-1H-di[1,3]oxazolo[3,4-d:4,3-g][1,4]diazepine-3,8-diones. Mild reaction conditions and the simplicity of isolation of the compounds formed make it possible to obtain the indicated heterocycles in high yields.     

A synthesis of 4H-thieno[3,2-c][1]benzopyran-4-ones by an application of the salicylidene-thiolactone rearrangement

Salicylidenes prepared from 5-ethyl-4-thiolen-2-one undergo base-catalyzed rearrangement (salicylidene-thiolactone rearrangement) to 4H-thieno[3,2-c][1]benzopyran-4-ones.     

Chemistry of acyl(imidoyl)ketenes

Thermal decarbonylation of 3-p-toluoylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-trione affords (2-oxo-1,4-benzoxazin-3-yl)(p-toluoyl)ketene. The latter enters into the [4+2]-cycloaddition reaction withp-bromobenzylidene-p-anisidine to form 1-p-bromophenyl-2-p-methoxyphenyl-4-p-toluoyl-1,2-dihydropyrimidino[4,3-c][1,4]benzoxazine-3,5-dione. The molecular and crystal structure of the title compound was studied by X-ray diffraction analysis. For Part 1, see Ref. 6; for Part 2, see Ref. 5. Deceased Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 614–617, March, 1999.     

Studies on the synthesis of heterocyclic compounds. Part IV. Further investigation of the pschorr reaction with some pyrazole derivatives

Thermal decomposition of the diazonium sulfate derived from N-methyl-(1-phenyl-3-methylpyrazol-5-yl)-2-aminobenzamide afforded products formulated as 1-phenyl-3-methyl[2]benzopyrano[4,3-c]pyrazol-5-one (yield 10%), 1,4-dimethyl-3-phenylpyrazolo[3,4-c]isoquinolin-5-one (yield 10%), N-methyl-(1-phenyl-3-methylpyrazol-5-yl)-2-hydroxybenzamide (yield 8%) and 4′-hydroxy-2,3′-dimethyl-1′-phenylspiro[isoindoline-1,5′-[2]-pyrazolin]-3-one (yield 20%). Decomposition of the diazonium sulfate derived from N-methyl-(1,3-diphenylpyrazol-5-yl)-2-aminobenzamide gave products formulated as 7,9-dimethyldibenzo[e,g]pyrazolo[1,5-a][1,3]-diazocin-10-(9H)one (yield 8%), 4-methyl-1,3-diphenylpyrazolo[3,4-c]isoquinolin-5-one (yield 7%) and 4′-hydroxy-2-methyl-1′,3′-diphenylspiro[isoindoline-1,5′-[2]pyrazolin]3-one (yield 10%). The spiro compounds 6a,b underwent thermal and acid-catalysed conversion into the hitherto unknown 2-benzopyrano[4,3-c]pyrazole ring system 7a,b in good yield. Analytical and spectral data are presented which supported the structures proposed.     

Three-component condensation of diethyl 2,4,6-trioxoheptanedicarboxylate with salicylaldehyde and ammonium acetate as a new method for the synthesis of the [1]benzopyrano[4,3-<Emphasis Type="Italic">b</Emphasis>]pyridine system

Three-component condensation of diethyl 2,4,6-trioxoheptanedicarboxylate with salicylaldehyde and ammonium acetate in EtOH affords 2,5-diethoxycarbonyl-5-hydroxy-4-oxo-4,4a, 5,10b-tetrahydro-1H-[1]benzopyrano[4,3-b]pyridine. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1494–1496, June, 2005.     

Synthesis of a rotenone-like benzopyranobenzopyranone

The synthesis of a novel rotenone-like molecule, 9-methoxy-8-methyl-6,6a,12,12a-tetrahydro[1]benzopyrano-[3,4-b][1]benzopyran-12-one ( 2 ) is described. Efficient syntheses of 3,4-dihydro-2H-[1]benzopyran-3-one ( 9 ) from ethyl 3-hydroxy-2H-[1]benzopyran-4-carboxylate ( 6 ), an intermediate in the synthesis of 2 , were developed. Thermolysis of 6 and 9 in decalin yielded 6,8-dihydro-14H-bis[1]benzopyrano[3,4-b:4′,3′-e]pyran-14-one ( 8 ), which has previously been described. Also produced in the thermolysis was the isomeric 1H-bis[1]-benzopyrano[3,4-b:3′,4′-á]pyran-7-(9H)one ( 10 ), the first member of a novel, pentacyclic ring system.     

Oxidative Addition of 4-Hydroxycoumarin to Alkenes. An Expeditious Entry to 2,3-Dihydro-4H-furo-[3,2-c][1]benzopyran-4-ones1

In the presence of one-electron metal oxidants (CAN, MAH), 4-hydroxycoumarin (1) adds to alkenes to give 2,3-dihydro-4H-furo[3,2-c][1]benzopyran-4-ones.