Synthesis of hydroxy-6H-benzofuro[3,2-c] [1]benzopyran-6-ones

The Micheal addition of ethyl 2-methoxy-, 2,4-dimethoxy- and 2,5-dimethoxybenzoylacetates with benzoquinone leads to ethyl 2-(rnethoxy or dimethoxy phenyl)-5-hydroxybenzofuran 3-carboxylates. Treatment of the henzofuran derivatives with anhydrous pyridine hydrochloride at 190–195° leads to hydroxy-6H-henzofuro[3,2-c] [1]benzopyran-6-ones.     

A new regioselective synthesis of 2,3,4,5-tetrahydro-6H-oxepino[3,2-c]pyran-6-ones,and [1]benzopyran-6-ones

Through an anti-Markovnikow hydration of some olefin derivatives of 4-hydroxy-2-pyrones, and 4-hydroxy-coumarins, followed by a regioselective intramolecular dehydration, involving the primary alcohols obtained and the enolic oxygen of the rings, promoted by Amberlyst 15 in boiling toluene, the new heterocycles 2,3,4,5-tetrahydro-6H-oxepino[3,2-c]pyran-6-one ( 3 ) and [1]benzopyran-6-ones ba,c were obtained in fair yields.     

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.     

Facile Regioselective Synthesis of 2-Methyl Furo [3,2-c][1] benzopyran-4-one 2-Methyl Furo[2,3-c] [1]benzopyran-4-one

The title compounds (7 &8) were obtained in excellent yields from 4-[2′-chloroprop-2′-enyloxy] [1] benzopyran-2-one (5) and 3-[2′-chloroprop-2-enyloxy][1]benzopyran-2-one (6) via [3,3] sigmatropic rearrangement and cyclisation of the intermediate chloroallylic enols with conc. H₂SO₄. The reaction was also studied in N,N-dimethyl aniline.     

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.     

[1,3]Dioxolo[5,6][1]benzothieno[2,3-c]-quinolin-6(5H)-ones

Summary The reaction of 3,4-methylenedioxycinnamic acid (1) with thionyl chloride resulted in the formation of 7-chlorothieno[2,3-f]-1,3-benzodioxole-6-carbonyl chloride (2) and cinnamoyl chloride (3). Subsequent reaction of the former withp-substituted anilines led to the formation of 7-chloro-N-(p-substituted phenyl)-thieno[2,3-f]-1,3-benzodioxole-6-carboxamides (4a–c) which on photocyclization afforded 2-substituted [1,3]dioxolo[5,6][1]benzothieno[2,3-c]quinolin-6(5H)-ones (5a–c) in fairly good yields and high purity. The structures have been confirmed by IR,¹H NMR, and analytical methods.Accepted for presentation at the Hong Kong International Symposium on Heterocyclic Chemistry (August 13–16, 1995)     

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.     

Synthesis of 6H,8H-isoquino[2,3-c][1,3]benzothiazin-8-ones

6H,8H-Isoquino-1,3-benzothiazin-8-ones have been prepared by reaction of 6,7-dimethoxy-2H-1,3-benzo-thiazines with homophthalic anhydride and by photocyclization of 3-benzoyl-4-methylene-6,7-dimethoxy 2H-1,3-benzothiazine. The compounds are thia analogues of protoberberine alkaloids containing a sulfur atom at C-5 and a lactam function at C-8. The mass spectra of the title compounds are discussed.     

The synthesis of [1]benzothieno[2,3-c]quinolines, [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline,and [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline

Photocyclization of 3-chloro-N-phenylbenzo[b]thiophene-2-carboxamide 10 afforded [1]benzothieno[2,3-c]-quinolin-6(5H)-one 11 which was chlorinated to 6-chloro[1]benzothieno[2,3-c]quinoline 12 followed by dechlorination to give [1]benzothieno[2,3-c]quinoline 5 . A series of 6-substituted alkoxy and thioalkoxy[1]benzothieno[2,3-c]quinoline derivatives were prepared along with the N-methyl quaternary salt 13 of 5 . 6-Chloro[1]-benzothieno[2,3-c]quinoline 12 was converted into 6-hydrazino[1]benzothieno[2,3-c]quinoline 23 which upon treatment with formic acid yielded [1]benzothieno[2,3-c][1,2,4]triazolo[4,3-a]quinoline 6 . Treatment of 23 with nitrous acid resulted in [1]benzothieno[2,3-c]tetrazolo[1,5-a]quinoline 7 . Compounds 6 and 7 are novel heterocyclic ring systems.     

Addition compounds of nucleophiles and 3-ethylthio-6-oxo-6H-1,2-dithiolo[4,3-c]1,2-dithiolium tetrafluoroborate. Synthesis of 3H,6H-1,2-dithiolo[4,3-c]1,2-dithiole-3-one-6-thione

Summary A smooth method of synthesizing 3H, 6H-1,2-dithiolo[4,3-c]1,2-dithiole-3,6-dithione (3), and also its partial desulfuration to yield 3H, 6H-1,2-dithiolo[4,3-c]1,2-dithiole-3-one-6-thione (4) is presented. The ethylation product5 of the monothione4 reacts with various nucleophilic reagents to form remarkably stable adducts. The adducts of5 with methanol,tert-butyl mercaptan, and with aniline could be isolated and characterized by their¹H-NMR spectra.

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Anlagerungsverbindungen von Nukleophilen an 3-Ethylthio-6-oxo-6H-1,2-dithiolo[4,3-c]1,2-dithioliumtetrafluoroborat. Synthese von 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3-on-6-thion

Zusammenfassung Eine glatte Synthese für 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3,6-dithion (3) und für dessen partielle Entschwefelung zu 3H,6H-1,2-Dithiolo[4,3-c]1,2-dithiol-3-on-6-thion (4) wird angegeben. Das Ethylierungsprodukt5 des Monothions4 reagiert mit unterschiedlichen Nukleophilen zu bemerkenswert stabilen Addukten. Die Addukte mit Methanol,tert.-Butylmercaptan und mit Anilin wurden isoliert und durch ihr¹H-NMR-Spektrum charakterisiert.

     

Synthesis of some 5H,12H-[1]benzoxepino[4,3-b]indol-6-ones. A new heterocyclic ring system

The synthesis of the title compounds 5H,12H-[1]benzoxepino[4,3-b]indol-6-ones 10 was effected by the Fischer indole cyclization of some 2,3-dihydro-4-phenylhydrazono[1]benzoxepin-5-ones 9 , obtained from the 3,4-dihydro-4-hydroxymethylene[1]benzoxepin-5(2H)-ones 7 by the Japp-Klingemann reaction. The structure of these new heterocyclic compounds was supported by ir, ¹H nmr and ms spectral data.     

Synthesis of 1H- and 2H-pyrazolo[3,4-c][2,1]benzothiazepines

Starting from ethyl chlorosulfonylpyrazole-4-carboxylates we have carried out the synthesis of ketones 3 and 4 which are the first two structures of the novel 1H- and 2H-pyrazolo[3,4-c][2,1]benzothiazepine ring systems.     

A Synthesis of 9-Methoxy-1-Methyl-1H,6H-Pyrazolo[4,3-c]Carbazole

The synthesis of 9-Methoxy-1-methyl-1H,6H-pyrazolo[4,3-c]carbazole is reported in four steps from 6-nitroindazole. Palladium acetate mediated cyclization gave only the “bent” tetracyclic derivative.     

Convenient Synthesis of [1,2,4]Triazolo[4,3-a][1,3,5]triazin-5-amines, [1,2,4]Triazolo[4,3-c][1,3,5]thiadiazine-5-thiones,and [1,2,4]Triazolo[4,3-c][1,3,5]thiadiazin-5-imines from N-(4H-1,2,4-Triazol-3-yl) Carboximidates

Russian Journal of Organic Chemistry - The condensation of 4H-1,2,4-triazol-3-amine with ortho esters derived from acetic, propionic, and benzoic acids gave the corresponding...     

Tricyclic heteroaromatic systems. 1,2,3,4-tetrahydropyrazolo[4,3-c][l]benzazepin-1-ones as potential antitumor agents

The synthesis of 1,2,3,4-tetrahydropyrazolo[4,3-c][1]benzazepin-1-ones 1 and that of its 10-methyl derivative 2 is reported. The preparation of the latter from 3-(2-aminobenzyl)3-pyrazolin-5-one and triethyl ortho-formate gave as the main product a derivative of the new tricyclic ring system, pyrazolo[1,5-c][1,3]benzo-diazepine. The structures of the new compounds synthesized were assigned by means of a ¹³C nmr study.