Hetero-Diels-Alder reaction of some 1,3-diaza-1,3-butadienes with ketenes. Synthesis of functionalized pyrimido[1,2-b]-benzothiazoles and 1,3,4-thiadiazolo-[3,2-a]pyrimidines

Summary Reaction of 1,3-diaza-1,3-butadienes (1a–c) with various ketenes and chloroketenes results in the formation of substituted 4-oxo-pyrimido[2,1-b]benzothiazoles (4a–d) and 1,3,4-thiadiazolo[3,2-a]pyrimido-4-ones (4e,f). Reaction of 1,3-diaza-1,3-butadienes1d,e with ketenes and chloroketenes leads to the 2-morpholine-substituted compounds7 and15, respectively. All reactions proceedvia formation of [4+2] cycloadducts that eliminate methylthiol, methylsulfenyl chloride, or morpholine.

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Hetero-Diels-Alder-Reaktion einiger 1,3-Diaza-1,3-butadiene mit Ketenen. Synthese funktionalisierter Pyrimido[1,2-b]benzothiazole und 1,3,4-Thiadiazolo[3,2-a]pyrimidine

Zusammenfassung Die Reaktion der 1,3-Diaza-1,3-butadiene1a–c mit verschiedenen Ketenen und Chlorketenen führt zu substituierten 4-Oxo-pyrimido[2,1-b]benzothiazolen (4a–d) und 1,3,4-Thiadiazolo[3,2-a]pyrimido-4-onen(4e,f). Die 1,3-Diaza-1,3-butadiene1d,e ergeben mit Ketenen und Chlorketenen die 2-Morpholin-substituierten Verbindungen7 und15. Alle Reaktionen verlaufen über [4+2]-Cycloaddukte, die Methylthiol, Methylsulfenylchlorid oder Morpholin eliminieren.

     

[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)     

Substituted benzimidazo[2,1 -h]pteridine-2,4-diones

5-Alkyl-5,6-dihydrobenzimidazo[2,1 -h]pteridine-2,4(1H,3H)-diones (4 a–d) have been synthesised by the condensation of 2-(alkyl-aminomethyl)benzimidazole dihydrochloride (1 a–d) with 5-bromobarbituric acid (2). Similarly, 5-alkyl-5,6-dihydro-4 a-nitrobenzimidazo[2,1 -h] pteridine-2,4(3H,4aH)-diones (10 a–d) have also been synthesised by the condensation of1 a–d with 5-bromo-5-nitrobarbituric acid (8) followed by cyclisation of the intermediate 5-[(benzimidazol-2-ylmethyl)alkylamino]-5-nitrobarbituric acid (9 a–d) with 5% NaOH. Thermal cyclisation of the intermediates9 a–d have also been studied. Methylation of the compound10 a has been carried out with CH₃I and K₂CO₃ usingD M F as solvent to confirm cyclisation. The structures are supported by elemental analyses, IR and PMR spectra.

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Substituierte Benzimidazo[2,1 -h]pteridin-2,4-dione

Zusammenfassung Die 5-Alkyl-5,6-dihydrobenzimidazo[2,1 -h]pteridin-2,4(1H,3H)-dione4 a-d wurden mittels Kondensation von 2-(Alkylaminomethyl)benzimidazolidhydrochloriden1 a–d mit 5-Brombarbitursäure (2) dargestellt. In ähnlicher Weise wurden die 5-Alkyl-5,6-dihydro-4a-nitrobenzimidazo[2,1 -h]pteridin-2,4(3H,4aH)-dione10 a–d über die Kondensation von1 a–d mit 5-Brom-5-nitrobarbitursäure (8) und nachfolgender Cyclisierung der intermediären 5-[(Benzimidazol-2-ylmethyl)alkylamino]-5-nitrobarbitursäuren9 a–d mit 5% NaOH dargestellt. Die thermische Cyclisierung der Produkte9 a–d wurde ebenfalls untersucht. Die Verbindungen wurden mittels Elementaranalyse, IR und PMR charakterisiert.

     

Synthesis and reactions of 2,3-dimethylfuro[3,2-c]pyridines

Summary A number of substituted 2,3-dimethylfuro[3,2-c]pyridines was synthesized. 3-(4,5-Dimethyl-2-furyl)propenoic acid (1) was converted to the acid azide2, which in turn was cyclized to give 2,3-dimethyl-5H-furo[3,2-c]pyridine-4-one (3) by heating at 240°C in Dowtherm. The pyridone3 was chlorinated with phosphorus oxychloride to give4, which was reduced with zinc and acetic acid to 2,3-dimethylfuro[3,2-c]pyridine (5). Treatment of4 with several secondary heterocyclic amines led to compounds6a–6c. Reaction of pyridone3 with phosphorus pentasulfide rendered the thione7, which was methylated to8a. The 4-methoxy derivative8b was obtained from4 with sodium methoxide. 2,3,5-Trimethylfuro[3,2-c]pyridine-4-one (9) was obtained by reaction of3 with methyl iodide.Dedicated to Professor Dr.Fritz Sauter on the occasion of his 65th birthday     

Synthesis of 4-methylfuro[3′,2′:5,6]benzofuro[3,2-c]pyridine

4-Methylfuro[3′,2′:5,6]benzofuro[3,2-c]pyridine ( 3 ) was synthetized from 2-acetylfuro[3,2-f]benzo[b]furan ( 4 ) or from 2-acetyl-5,6-dihydrofuro[3,2-f]benzo[b]furan ( 10 ). The key step involves a rearrangement-cyclization of azides 6 and 12 to form 4-methylfuro[3′,2′:5,6]benzofuro[3,2-c]pyridin-1(2H) one ( 7 ) and 8,9-dihydro-4-methylfuro[3′,2′:5,6]benzofuro[3,2c]pyridin-1(2H)-one ( 13 ). Introduction of an aminoalkyl chain on carbon 1 was effected by substitution of 1-chloro-4-methylfuro[3′,2′:5,6]benzofuro[3,2-c]pyridine ( 8 ).     

Synthesis of 2-aryl-6,6-dimethyl-8-oxo-5,6,7,8-tetrahydro-1,2,4-4H-triazolo[3,2-b]benzothiazoles and their 3-aryl-[3,4-b] isomers

Summary Condensation of 3-aryl-5-thio-1,2,4-4H-trizoles (2a–i) and 2-bromodimedone (3) inTHF/benzene gave 2-aryl-6,6-dimethyl-8-oxo-5a-hydroxy-5,5a,6,7,8,8a-hexahydro-1,2,4-4H-triazolo[3,2-b]benzothiazoles (5a–i). These were also obtained by a one step synthesis on heating a mixture of dimedone,NBS, and2a–i in benzene containing a trace of benzoyl peroxide. Thermal dehydration of5a–i inPPA/anhydrous ethanol yielded the corresponding 2-aryl-6,6-dimethyl-8-oxo-5,6,7,8-tetrahydro-1,2,4-4H-triazolo[3,2,b]benzothiazoles (6a–i). The formation of [3,4-b] fused isomers (4a–i) during the reaction of2 with3 was ruled out by an unambiguous synthesis of8a–i. Antibacterial screening of selected compounds againstEscherichia coli andStaphylococcus aureus was not encouraging.

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Synthese von 2-Aryl-6,6-dimethyl-8-oxo-5,6,7,8-tetrahydro-1,2,4-4H-triazolo[3,2-b]benzothiazolen und ihrer 3-Aryl-[3,4-b]-Isomeren

Zusammenfassung Die Kondensation von 3-Aryl-5-thio-1,2,4-4H-triazolen (2a–i) mit 2-Bromdimedon (3) inTHF/Benzol ergab 2-Aryl-6,6-dimethyl-8-oxo-5a-hydroxy-5,5a,6,7,8,8a-hexahydro-1,2,4,-4H-triazolo[3,2-b]benzothiazole (5a–i). Dasselbe Ergebnis wurde durch Erhitzen einer Mischung von Dimedon,NBS und2a–i in Benzol unter Zusatz einer Spur Benzoylperoxid in einer einstufigen Synthese erreicht. Thermische Dehydrierung von5a–i inPPA/Ethanol(abs.) ergab die entsprechenden 2-Aryl-6,6-dimethyl-8-oxo-5,6,7,8-tetrahydro-1,2,4-4H-triazolo[3,2-b]benzothiazole (6a–i). Die Bildung [3,4-b]-kondensierter Isomere (4a–i) während der Reaktion von2 mit3 konnte durch eine eindeutige Synthese von8a–i ausgeschlossen werden. Antibakterielles Screening ausgewählter Verbindungen gegenüberEscherichia coli undStaphylococcus aureus brachte keine ermutigenden Resultate.

     

DMF acetals as alkylating and cyclizing agents: A facile route to substituted pyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-diones

Summary Several 7-methyl-5-alkyl-2-vinylpyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-diones were prepared. The successful cyclization and alkylation of 6-(-methylbenzylidenehydrazino)-1-methyluracils2a–d using dimethylformamide acetals at high temperature provided6a–d,7a–d, and8a–d. Treatment of6a–d and7a–d with acid afforded 7-methyl-5-alkylpyrazolo[3,4-d]pyrimidine-4,6(5H,7H)-diones9a,b; under the same conditions,3a–d reacted to 7-methylpyrazolo[3,4-d]-pyrimidine-4,6(5H)-dione (4) in good yield.

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DMF-Acetale als Alkylierungs- und Ringschlußreagentien: ein einfacher Weg zu substituierten Pyrazolo[3,4-d]pyrimidin-4,6(5H,7H)-dionen

Zusammenfassung Es wurden verschiedene 7-Methyl-5-alkyl-2-vinylpyrazolo[3,4-d]pyrimidin-4,6(5H,7H)-dione hergestellt. Cyclisierung und Alkylierung der 6-(-Methylbenzylidenhydrazino)-1-methyl-uracile2a–d mit Hilfe von Dimethylformamidacetalen bei hohen Temperaturen ergab6a–d,7a–d und8a–d. Behandlung von6a–d und7a–d mit Säure lieferte die 7-Methyl-5-alkylpyrazolo[3,4-d]pyrimidin-4,6(5H,7H)-dione9a,b; unter den gleichen Bedingungen reagierten3a–d in guter Ausbeute zu 7-Methylpyrazolo[3,4-d]pyrimidin-4,6(5H)-dion (4).

     

Saturated heterocycles, 75. Preparation of tetracyclic thiophene derivatives with bridgehead nitrogen. Synthesis of polymethylenethieno[2,3—d]dihydropyrrolo-, tetrahydropyrido- and tetrahydroazepino[1,2—a]pyrimidin-4-ones and -4-thiones

The following tetracyclic ring systems and their derivatives have been synthesized for pharmacological investigations: Trimethylenethieno[2,3—d]dihydropyrrolo[1,2—a]pyrimidin-4-one and -4-thione (1 a, 5 a); Tetramethylenethieno[2,3—d]dihydropyrrolo[1,2—a]pyrimidin-4-one and -4-thione (1 b, 1 j, 5 b); Pentamethylenethieno[2,3—d]dihydropyrrolo[1,2—a]pyrimidin-4-one and-4-thione (1 c, 5 c); Trimethylenethieno[2,3—d]tetrahydropyrido[1,2—a]pyrimidin-4-one and -4-thione (1 d, 5 d); Tetramethylenethieno[2,3—d]tetrahydropyrido[1,2,—a]pyrimidin-4-one and -4-thione (1 e, 5 e); Pentamethylenethieno[2,3—d]tetrahydropyrido[1,2—a]pyrimidin-4-one and -4-thione (1 f, 5 f); Trimethylenethieno[2,3—d]tetrahydroazepino[1,2—a]pyrimidin-4-one and -4-thione (1 g, 5 g); Tetramethylenethieno[2,3—d]tetrahydroazepino[1,2—a]pyrimidin-4-on and -4-thione (1 h, 5 h); Pentamethylenethieno[2,3—d]tetrahydroazepino[1,2—a]pyrimidin-4-one and -4-thione (1 i, 5 i); Tentamethylenethieno[2,3—d]tetrahydroazepino[1,2—a]pyrimidin-4-one (7 b); Pentamethylenethieno-[2,3—d]tetrahydropyrido[1,2—a]pyrimidin-4-one (7 c).Compounds1 a–i were synthesized from 2-amino-3-ethoxycarbonyl-4,5-polymethylenethiophene2 a–c with the corresponding lactim ethers (3 a–c) in chlorobenzene in the presence of polyphosphoric acid (PPA). Compounds7 b and7 c were obtained in the reaction of -amino acid esters2 b and2 c with 2-bromopyridine (6). The thione derivatives (5 a–i) were prepared from compounds1 a–i with phosphorus(V) sulphide.Part 74:Szabó J, Fodor L, Szcs E, Bernáth G, Sohár P (1984) Pharmazie 39: 347.     

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 and Reactions of 4-Oxiranylmethylfuro[3,2-b]pyrroles and Their Benzo Derivatives

Methyl 4-oxiranylmethyl-4H-furo[3,2-b]pyrrole-5-carboxylates 2a-c and methyl 1-oxiranylmethyl-1H-benzo[4,5]furo[3,2-b]pyrrole-2-carboxylate (2d) were prepared by reaction of the appropriate starting compounds 1a-d with excess chloromethyloxirane. The compounds 2a-d undergo oxirane ring opening by heterocyclic amines (morpholine, pyrrolidine, piperidine or 4-methylpiperazine) giving N-2-hydroxy-3-heteroaminopropyl-substituted compounds 3a-f or substituted 4,5-dihydrofuro[2',3':4,5]pyrrolo[2,1-c][1,4]oxazin-8-ones 4a-e.     

Condensed pyridazines. Part IV. Reductive cyclization of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-rnethylacrylatc (I) to pyrido[2,3-c] pyridazines and the acid-catalysed cyclization of I to a pyrano[2,3-d] pyridazine

Reduction followed by cyclization of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate (I) to pyrido[2,3-c]pyridazines by treatment with triethyl phosphite or hydrazine hydrate as the reducing agents is described. Compound I was also reductively cyclized with sodium borohydride. Treatment of I with concentrated sulfuric acid gave 8-chloro-3,6-dimethyl-2,5-dioxo-5,6-dihydro-2H-pyrano[2,3-d] pyridazine (VII) which also could be synthesized by another independent route. A mechanism for the cyclization is proposed.     

Synthesis and spectral properties of substituted 4-chlorooxazoloquinolines

Summary The treatment of a mixture of linearly and angularly annelated 2-substituted oxazolo[4,5-f]quinolones (5a–c) and oxazolo[5,4-g]quinolones (6a–c) and similarly the treatment of 2-substituted oxazolo[5,4-f]quinolones (7a–c) and oxazolo[4,5-g]quinolones (8b,c) with POCl₃ afforded substituted 4-chlorooxazolo[4,5-f]quinolines (9a–c) and 2-substituted 4-chlorooxazolo[5,4-f]quinolines (10b,c), respectively. Spectral characteristics of the synthesized derivatives (¹H and¹³C NMR, IR, UV, and MS) are discussed.Dedicated to Prof.Fritz Sauter on the occasion of his 65th birthday     

Synthesis of 2H-pyrano[2,3-d]pyrimidine derivatives

Two series of 2H-pyrano[2,3-d]pyrimidine-2,5(6H)-dione derivatives have been prepared. Thus, the reaction of 6-hydroxy-pyrimidin-4(3H)-ones (1 a–c) with bis-2,4,6-trichlorphenyl malonates (2 a–d) or diethyl malonates (3 a–d) afforded good yields of 4-hydroxy-2H-pyrano[2,3-d]pyrimidine-2,5(6H)-diones (4 a-l). Application of our modifiedPechmann reaction^9–11 using -aminocrotonate (5) or -keto esters (6, 7) in the presence of ammonium acetate yielded the 2H-pyrano[2,3-d]pyrimidinediones8 a–h.Dedicated to Prof. Dr.Karl Schlögl, University of Vienna, on the occasion of his 60th birthday.     

Pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9(6H8H)-diones

Some 5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9-(6H,8H)-diones (4 a–d) have been synthesised by the condensation of 3-alkyl-4-amino-5-mercapto-(1,2,4)-triazoles (1 a–d) with 5-bromobarbituric acid (2a). Similarly some 9a-nitro-5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazine-7,9(8H,9aH)-diones (5 a–d) have been obtained by the condensation of1 a–d with 5-bromo-5-nitrobarbituric acid (2b) and final cyclisation withPPA. The structures have been confirmed by PMR spectra and analytical results.

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Pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(6H,8H)-dione

Zusammenfassung Es wurden einige 5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(6H,8H)-dione (4 a–d) mittels Kondensation von 3-Alkyl-4-amino-5-mercapto-(1,2,4)-triazolen (1 a–d) mit 5-Brombarbitursäure (2 a) dargestellt. Des weiteren wurden einige 9a-Nitro-5H-pyrimido[4,5-e](1,2,4)-triazolo[3,4-b](1,3,4)-thiadiazin-7,9(8H,9aH)-dione (5 a–d) über die Kondensation von1 a–d mit 5-Brom-5-nitrobarbitursäure (2 b) und anschließender Cyclisierung mitPPA synthetisiert. Die angeführten Strukturen wurden mittels PMR-Spektren und analytischen Daten abgesichert.

     

Zur Kenntnis der Reaktionsfähigkeit alkylsubstituierter Thiomorpholine, 1. Mitt.

Zusammenfassung Die Darstellung einigerMannichbasen (3 a-f) bzw.Mannich-basen-hydrochloride (2 a-f) und zahlreicher s-Triazin-Derivate (4 a-d, 5 a–m, 6 a–w, 7 a–e, 8 a–d, und9 a–l) auf Basis des unsubstituierten Thiomorpholins (1 a) sowie C-mono-[2-Methylthiomorpholin (1 b) und 2-Äthylthiomorpholin (1 c)] und C-dialkylierter Thiomorpholine [2-Methyl-3-äthylthiomorpholin (1 d)] wird beschrieben.

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Concomitant action of elementary sulfur and gaseous ammonia upon ketones, LXXIX: On the reactivity of alkyl substituted thiomorpholines, I

The preparation of someMannichbases (3 a-f) andMannich base hydrochlorides (2 a-f), resp., and numerous s-triazine derivatives (4 a-d, 5 a–m, 6 a–w, 7 a–e, 8 a–d, and9 a–l) based upon unsubstituted thiomorpholine (1 a) as well as C-mono-[2-methylthiomorpholine (1 b) and 2-ethylthio-morpholine (1 c)] and C-dialkylated thiomorpholines [2-methyl-3-ethylthiomorpholine (1 d)] is described.

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HerrE. Wilms dankt der Deutschen Texaco AG. für die Gewährung eines Stipendiums herzlichst.     

Convenient synthesis and anticancer evaluation of novel pyrazolyl-thiophene,thieno[3,2-b]pyridine,pyrazolo[3,4-d]thieno[3,2-b]pyridine and pyrano[2,3-d]thieno[3,2-b]pyridine derivatives

The newly synthesized 3-(3-amino-5-(phenylamino)-4-(phenylcarbamoyl)thiophen-2-yl)-3-oxopropanoate was utilized as a precursor for the synthesis of pyrazolyl-thiophene derivative, which undergoes cyclization upon treatment with benzaldehyde derivatives to provide pyrazolo[3,4-d]thieno[3,2-b]pyridines. Basic treatment of pyrazolyl-thiophene derivative with phenyl isothiocyanate followed by subsequent addition of chloroacetone and/or ethyl bromoacetate yielded the thiazolylidene-pyrazolyl thiophenes. In addition, the building block 3-(3-amino-5-(phenylamino)-4-(phenylcarbamoyl)thiophen-2-yl)-3-oxopropanoate was converted into the corresponding thieno[3,2-b]pyridine compounds through its reactions with (DMF-DMA) and/or heating in sodium ethoxide. Moreover, the reaction of 7-hydroxy-5-oxo-N-phenyl-2-(phenylamino)-4,5-dihydrothieno[3,2-b]pyridine-3-carboxamide with 2-arylidenemalononitrile produced the new annulated pyrano[2,3-d]thieno[3,2-b]pyridines. The prepared thiophene-based compounds were evaluated against HepG2, PC3, and MCF-7 cancer cells, and normal fibroblast cell (WI38). The pyrazolo[3,4-d]thieno[3,2-b]pyridine and pyrano[2,3-d]thieno[3,2-b]pyridine compounds substituted with chlorophenyl group presented promising cytotoxic activities against HepG2 cancer cell line without any human toxicity. Docking study for the synthesized thiophene compounds delivered valuable insights about the binding interactions with the crystal structure of NS5B enzyme with PDB ID (4TLR).     

Synthesis and cytotoxic evaluation of novel brominated N-alkyl pyrano[3,2-c]quinolinones

A novel series of 6-alkyl-4-bromopyrano[3,2-c]quinoline-2,5-diones ( 2a–c ), 6-alkyl-3,4-dibromopyrano[3,2-c]quinoline-2,5-diones ( 4a–c ), and 6-alkyl-3-amino-bromopyrano[3,2-c]quinoline-2,5-diones ( 6a–c ) were synthesized via appropriate conventional methods and in good yields. The structures of target compounds were approved by elemental analysis, IR, ¹H NMR, ¹³C NMR, and mass spectrometry. The antitumor inhibitory activities of the new compounds were evaluated on several cancer cell lines, A-549 (human lung cancer), HCT-116 (human colon cancer), MCF-7 (breast cancer), and HePG-2 (human liver cancer). Moreover, 50% inhibitory concentrations, IC₅₀, were established. 5-Fluorouracil was used as a positive control in the viability assay. The screening results showed that most of the examined compounds exposed powerful inhibition activity toward various cell lines. Particularly, Compound 4c exhibited higher cytotoxic activity against four tumor cell lines than the reference drug, 5-fluorouracil, with significantly lower IC₅₀ values. Accordingly, most of the synthesized compounds would be a better prospective growth in the anticancer drug discovery.     

A reinvestigation of the synthesis of 3H-[1,2]diazepino[5,6-b]indoles. The synthesis of pyrido[4,3-b]indoles

Recently reported [1] syntheses of 6-methyl-1,2,4,5-tetrahydro-1,4-dioxo-3H[1,2]diazepino[5,6-b]indole ( 5 ) and 4-hydroxy-6-methyl-3H[1,2]diazepino[5,6-b]indole ( 12 ) were reinvestigated and shown to be in error. The correct assignments for these respective structures are 3-amino-1,9-dihydro-9-methyl-2H-pyrido[4,3-b]indol-2,4(3H)-dione ( 6 ) and 3-amino-3,9-dihydro-9-methyl-2H-pyrido[4,3-b]indol-2-one ( 13 ). Condensation of 6 and 13 with p-nitrobenzaldehyde produced benzylidene derivatives, which confirmed the presence of the amino groups.     

Furopyridines. XI. 13C NMR Spectra of 2- or 3-Substituted Furo[2,3-b]-, Furo[3,2-b]-, Furo[2,3-c]- and Furo[3,2-c]pyridine

The ¹³C nmr spectra of 2- or 3-monosubstituted furo[2,3-b]- 1a-1j , furo[3,2-b]- 2a-2j , furo[2,3-c]- 3a-3j and furo[3,2-c]pyridine derivatives 4a-4j are reported. Effects by change in annelation and substituent effects on ¹³C chemical shifts and carbon-proton coupling constants are discussed. The spectra of benzo[b]furan derivatives 5a-5j having the corresponding substituent are also reported for comparison.     

12H-naphtho[1′,2′:5,6]pyrano[2,3-d]pyrimidine derivatives

Reaction of 1-oxo-2-formyl-3-dimethylamino-1H-naphtho[2,1-b]pyran with amidines, guanidine, O-methylisourea, S-methylisothiourea afforded 9-substituted 12-oxo-12H-naphtho[1′,2′:5,6]pyrano[2,3-d]pyrimidines. When the reaction with O-methylisourea was carried out in anhydrous pyridine, 10,20-dioxo-10H,20H-dinaphtho[1,2-e:1′,2′-e′][1,5]diazocino[2,3-b:6,7-b′]dipyran was formed.