Synthesis of benzo[a]furo[2,3-g]quinolinzines from 2-methyl-2-cinnamoyloxirane

Stereoisomeric le-allyl-3-hydroxy-3-methyl-6e-phenyl-4-piperidones were obtained by reaction of 2-methyl-2-cinnamoyloxirane with allylamine. Their PO-olefinization and subsequent heating in 96% H₂SO₄ leads to 3a,4,6,7,11b,12-hexahydro-3a,7-dimethyl-2-oxobenzo[a]furo[2,3-g]quinolizines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1269–1272, September, 1989.     

Synthesis of 2,3,10,11 -tetraalkoxy-substituted tetrahydrobenzo [a] naphtho [1,2-g] quinolizines

2 Four3,10,11-tetraalkoxy-substituted 5,6,15,15a-tetrahydro-8H-benzo[a]naphtho[1,2-g]-quinolizines were prepared by the Pictet-Spengler cyclization of the respective 1-(6,7-dialkoxy-2-naphthylmethyl)-6,7-dialkoxy-1,2,3,4-tetrahydroisoquinolines. The latter compounds were obtained by a chemical reduction of the corresponding dihydro compounds, which, in turn, were formed by a Bischler-Napieralski cyclization of the appropriate amides.     

Synthesis of 3-amino derivatives of benzo[b]furo[2,3-c]pyridines

The reaction of 1,7-dimethyl-3(2H)-benzo[b]furo[2,3-c]pyridone with phosphoric acid amides gave 1,7-dimethyl-3-dimethylamino (morpholino)benzo[b]furo[2,3-c]pyridines. A method for the synthesis of 3-amino derivatives of 4-nitrobenzo[b]furo[2,3-c]pyridines, which consists in heating 1,7-dimethyl-4-nitro-3(2H)-benzo[b]furo[2,3-c]pyridone with hexamethyldisilazane and secondary or primary amines in pyridine, was developed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1552–1555, November, 1991.     

The synthesis of some pyrano[2,3-g]chromene-2,7-diones and furo[2,3-g]chromen-6-ones

The o-hydroxyformylcoumarin 5b , easily prepared from compound 1 , is further transformed to the title coumarin derivatives 7, 10, 19a-c via its initial Wittig olefination with ylides 2b, 8, 18a-c respectively. Coumarins 16a, b were also formed by treatment of 5b with compounds 15a, b . The preparation of the interesting furocoumarin derivatives 11, 14, 20b, c as well as of compound 13 is also described.     

1,4-Cycloaddition reactions. III. Synthesis of furo[3,2-c]pyrido[2,3-g]quinolines,Furo[2,3-a] [4,7]phenanthrolines,Furo[3,2-c]pyrrolo[2,3-g]quinolines,Furo[3,2-c]pyrrolo[3,2-g]quinolines,and Furo[3,2-c]furo[2′,3′:4,5]pyrido[2,3-g]quinolines from 2,3-dihydro-5-methylfuran and schiff bases

The 1,4-cycloaddition of 2,3-dihydro-5-methylfuran (II) to 1-acetyl-1,2,3,4-te trahydro-6-[(p-hydroxybenzylidene)amino]quinoline (VIII) in the presence of boron trifluoride gave two pairs of epimers, namely dl-10-acetyl-2,3,3a,4,5,7,8,9,10,11b-decahydro-4-(p-hydroxyphenyl)-11b-methylfuro[3,2-c]pyrido[2,3-g]quinoline (IXa and b) and dl-8-acetyl-2,3,3a,4,5,8,9,10,11,-11c-decahydro-4-(p-hydroxyphenyl)-11c-methylfuro[2,3-a][4,7]phenanthroline (Xa and b). dl-9-Acetyl-3,3a,4,5,7,8,9,10b-octahydro-4-(p-hydroxyphenyl)-10b-methyl-2H-furo[3,2-c] pyrrolo-[2,3-g]quinoline (XIIIa) was the predominant product isolated from the reaction of II with 1-acetyl-5-[p-(hydroxybenzylidene)amino]indoline (XII). When 1-acetyl-6-[(p-hydroxybenzylidene)amino]indoline (XVI) was treated with 2,3-dihydro-5-methylfuran (II), two epimers of dl-7-acetyl-3,3a,4,5,7,8,9,10b-octahydro-4-(p-hydroxyphenyl)-10b-methyl-2H-furo[3,2-c]pyrrolo[3,2-g]quinoline (XVIIa and b) were obtained. dl-2,3,3a,4,5,6b,8,9,9a,10,11,12b-Dodecahydro-4,10-bis(p-methoxyphenyl)-6b,12b-dimethylfuro[3,2-c]furo[2′,3′:4,5]pyrido[2,3-g]quinoline (XX) was formed when 2,3-dihydro-5-methylfuran was allowed to react with N,N'-bis(p-methoxybenzylidene)-p-phenylcnediamine (XIX). Structure assignments were made from NMR spectra. None of the compounds exhibited appreciable biological activity.     

1,4-Cycloaddition reactions. II. Preparation of p-dioxino[2,3-g]furo[3,2-c] quinolines,p-dioxino[2,3-f] furo[3,2-c] quinolines,and [1,3] dioxolo[4,5-g] furo[3,2-c] quinolines from 2,3-dihydro-5-methylfuran and schiff bases

The boron trifluoride catalyzed 1,4-addition of 2,3-dihydro-5-methylfuran to N-(p-methoxy-benzylidene)-1,4-benzodioxan-6-amine (II) gave 2 pairs of epimers, 2,3,3a,4,5,8,9,11b-octahydro-4-(p-methoxyphenyl)-11b-methyl-p-dioxino[2,3-g]furo[3,2-c]quinoline (IIIa and b) and 2,3,7,8,8a,9.10,1la-octahydro-8-(p-methoxyphenyl)-11a-methyl-p-dioxino[2,3-f]furo[3,2-c]quinoline (IVa and b). When N-(p-methoxybenzylidene)-3,4-methylenedioxyaniline (V) was condensed with 2,3-dihydro-5-methylfuran in an analogous manner, a mixture of 2 epimers of 2,3,3a,4,5,10b-hexahydro-4-(p-methoxyphenyl)-10b-methyl[1,3]dioxolo[4,5-g]furo[3,2-c]quinoline (VIa and b) was isolated. Treatment of this mixture with sulfur afforded 6-(p-methoxyphenyl)-8-methyl-1,3-dioxolo[4,5-g]quinoline-7-ethanol (VIII). Structural assignments for all of the products were made from NMR spectra. None of the compounds possessed appreciable biological activity.     

Synthesis and reactions of benzo[b]furo[2,3-c]pyrylium salts

A method has been developed for the synthesis of 3-acetonyl- and 3-phenacylben-zo[b]furans by cyclization of 1-arloxy-2,4-pentanediones and 1-phenyl-4-aryloxy-1,3-butanediones in polyphosphoric acid. Acylation of 3-acetonyl(phenyl-benzo-[b]furans with aliphatic acid anhydrides in the presence of perchloric acid gives the benzo[b]furo[2,3-c]pyrylium perchlorates. The recyclization of the pyrylium salts with ammonia, aqueous alkali, and morpholine has been examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 889–893, July, 1987.     

Synthesis of 3-hydroxy-3-methyl-7-phenylbenzo[a]quinolizin-2-ones

Amino alcohols were prepared by debenzylation of l-benzyl-3-hydroxy-3-methyl-6(e) Phenyl-4 piperidone ethylene ketals, alkylation with phenacyl bromide, and subsequent reduction of the carbonyl group, and holding the alcohol in a mixture of sulfuric and trifluoroacetic acids yields 3-hydroxy-3-methyl-7(e)-pherrylbenzofafquirrolizin-2-ones. The possibility of recyclization of the latter while boiling in a mixture of acetic anhydride and acetic acid by -ketol rearrangement or rupture of the C-N bond was demonstrated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 221–224, February, 1994. Original article submitted January 18, 1994.     

New method for the synthesis of 8-azasteroids: Synthesis of benzo[a]cyclohexa[f]furo[2,3-g]-quinolizines from 2-cinnamoylcyclohexa[b]oxirane

The reaction of 2-cinnamoylcyclohexa[b]oxirane with allylamine gave cis-2(),3,4a,5,6,7,8,8a()-octahydro-1-allyl-4a()-hydroxy-(2)-phenylquinolin-4-one, which upon subsequent reaction with dimethyl malonate, peroxide epoxidation, and heating with hydrochloric acid gave cis-4,5,6a(),7,8,9,10a-octa-hydro-6-allyl-20-oxo-5()phenyl-3-chlorofuro[3,2-d]quinoline. Heating of this intermediate in 96% sulfuric acid gavetrans-3a(a),7a(a),9,10(),14b(),15-hexahydro-10()-methyl-2-oxo-1-chlorobenzo[a]cyclo-hexa[f]furo[2,3-g]quitiolizine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 30, No. 3, pp. 411–414, March, 1994.     

Synthesis of a peralkynylated pyrazino[2,3-g]quinoxaline

[structure: see text] The synthesis of a hexaethynyl[2,3-g]pyrazinoquinoxaline and its crystal structure are reported. Starting from tetraaminobenzoquinone, condensation to bis(triisopropylsilyl)hexadiyne-2,3-dione affords 2,3,7,8-tetrakis(triisopropylsilylethynyl)pyrazino[2,3-g]quinoxaline-5,10-dione. Reaction with TIPS-CC-Li followed by reduction with hypophosphite in the presence of KI furnished the title molecule in a yield of 62%. Pd catalysis is not involved in any of these steps.     

Synthesis of furo[2,3-b]pyridine

Two routes were employed to synthesize unsubstituted furo[2,3-b]pyridine (IV). The first method started with ethyl 5-aminofuro[2,3-b] pyridine-2-carboxylate (1) and involved successive deamination, hydrolysis, and decarboxylation. The second method began with 5-nitrofuro[2,3-b ]-pyridine-2-carboxylic acid (V) and consisted of successive decarboxylation, reduction, and deamination reactions.     

Synthesis of 2-N,N-dimethylaminomethyl-2,3,3a,12b-tetrahydrodibenzo-[b,f]furo[2,3-d]oxepin derivatives as potential anxiolytic agents

New synthesis approaches that have led to a series of novel tetrahydrodibenzo[b,f]furo[2,3-d]oxepin derivatives are described. According to preliminary data these novel tetracycles can be useful intermediates for the preparation of potential new therapeutic agents.     

Synthesis of thia-ellipticine, 5,11-dimethylbenzothieno[2,3-g]isoquinoline

1,4-Dimethyldibenzothiophene (VII) was synthesized and was converted with butyl dichloromethyl ether to the 2-aldehyde (VIII). The structure was confirmed by an independent synthesis of the 2-ester (XI) derived from it. The 2-aldehyde (VIII) with aminoacetaldehyde diethylacetal formed the Schiff′s base (IX), and Pomeranz-Fritsch cyclization with 105% superphosphoric acid then formed thia-ellipticine (II), an isostere of the antitumor alkaloid, ellipticine.     

Synthesis of furo[2,3-f]- and furo[3,2-e]indole derivatives

Two compounds — the diethylamides of 1,2-dimethyl-3-carbethoxy-6-carboxyfuro[2,3-f]- and 1,2-dimethyl-3-carbethoxy-5-carboxvfuro[3,2-e]indoles — are formed in the reaction of 1,2-dimethyl-3-carbethoxy-5-hydroxyacetic acid (I) with dimethylformamide and phosphorus oxychloride as a result of subsequent intramolecular cyclization of the intermediates. This constitutes evidence for formylation of the starting acid in the 6 and 4 positions. Formylation of the ethyl ester of acid I gives only the 6-formyl derivative, the intramolecular cyclization of which under the influence of sodium ethoxide gives 1,2-dimethyl-3,6-dicarbethoxyfuro[2,3-f]-indole. Hydrolysis of the latter with alcoholic alkali gives the corresponding dicarboxylic acid. The structures of the synthesized compounds were confirmed by the PMR, IR, and mass spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 766–769, June, 1977.     

Furopyridines. XIV. Synthesis of 2-aminoalkyl derivatives of furo[2,3-b]-, furo[3,2-b], furo[2,3-c]- and furo[3,2-c]pyridine

The preparation of 2-aminomethyl- 3a-d , 2-acetamidomethyl- 4a-d , 2-N,N-dimethylaminomethyl- 5a-d , 2-(1-hydroxy-2-nitroethyl)- 6a-d , 2-(1-hydroxyl-2-aminoethyl)- 7a-d and 2-(1-hydroxy-2-N,N-dimethylaminoethyl)- 8b-d derivatives of furo[2,3-b]-, furo[3,2-b]-, furo[2,3-c]- and furo[3,2-c]pyridine is described.     

Synthesis of furo[b]tropylium tetrafluoroborate

The first synthesis and characterization of the title compound are described.     

Synthesis of 2H-benzo[2,3-g]pyridazino-[4,5-d,e]quinolin-3-one derivatives

Summary Condensation-cyclization of hydrazine with 4-methoxycarbonylbenzo[g]quinolinequinone or its corresponding carboxylic acid afforded 7-hydrazino-2H-benzo[2,3-g]pyridazino[4,5-d,e]-quinolin-3-one. Starting with the 9-hydroxy derivative, a similar double condensation of the nucleophile was observed, whereas its 6-hydroxylated regioisomer gave 2H-benzo[2,3-g]pyridazino-[4,5-d,e]quinolin-3,7-dione.

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Synthese von 2H-Benzo[2,3-g]pyridazino[4,5-d,e]chinolin-3-on-Derivaten

Zusammenfassung Die Kondensation/Zyklisierung von Hydrazin mit 4-Methoxycarbonylbenzo-[g]chinolinchinon bzw. mit der entsprechenden Carbonsäure ergab 7-Hydrazino-2H-benzo[2,3-g]-pyridazino[4,5-d,e]chinolin-3-on. Ausgehend vom 9-Hydroxy-Derivat, wurde in analoger Weise doppelte Kondensation des Nucleophils beobachtet, wohingegen das 6-Hydroxy-Regioisomer zu 2H-Benzo[2,3-g]pyridazino[4,5-d,e]chinolin-3,7-dion reagierte.