Parallel Synthesis of Pyrrolo[3,2-f]quinolines (PQQ Skeleton) Library via a One-Pot Three-Component Reaction under Catalyst-Free Conditions

An efficient and straightforward synthetic protocol was developed for the diversity-oriented synthesis of 13-aryl-6,13-dihydrochromeno[4,3-b]pyrrolo[3,2-f]quinolin- 12(3H)-one and 10-aryl-3H-furo[3,4-b]pyrrolo[3,2-f]quinolin-9(7H)-one derivatives (PQQ skeleton) in high yields under catalyst-free conditions. This procedure includes a one-pot three-component reaction of aromatic aldehyde, 1H-indol-5-amine, and 1,3-dicarbonyl compounds to generate total of 25-Membered structurally interesting and pharmacologically significant PQQ skeletons for bio-active screening.     

Cyclofunktionalisierung von 2-Allyl-phenolen mit Schwefelchloriden. III. 2-Arylthiomethyl-2,3-dihydrofuro[3,2-h]chinoline aus 7-Allyl- bzw. 7-Methallyl-8-hydroxychinolin und Aryl-sulfenylchloriden

Cyclofunctionalization of 2-Allyl-phenols with Sulfur Chlorides. III. 2-Arylthiomethyl-2,3-dihydrofuro[3,2-h] quinolins from 7-Allyl- and 7-Methallyl-8-hydroxyquinoline, respectively, and Arylsulfenyl Chlorides Reactions of 7-allyl- ( 3 ) and 7-methallyl-8-hydroxyquinoline ( 4 ) with selected arylsulfenyl chlorides ( 5a – d ) yield the products of cyclofunctionalization corresponding 2-arylthiomethyl-2,3-dihydrofuro[3,2-h]quinolins ( 6 and 7 ). The products are identified by ¹H-n.m.r.-spectroscopy, mass spectrometry and microanalyses.     

5,6,7-Trihydro-5,7-diphenyl-thiazolo[3,2-b]-s-triazin-3 (2h)-one as a stabilizer for the double base propellant

5,6,7-Trihydro-5,7-diphenyl-thiazolo [3,2-b]-s-triazin-3(2H)-one (C₁₇H₁₅N₃OS) is used as a stabilizer for the double base propellant and gave good results with the stability tests. The samples were stored for 12 days at 100° C and were extracted by different suitable solvents. The column partition chromatography helped in separation of 5,6,7-trihydro-5,7-(2-nitrodiphenyl)-thiazolo[3,2-b]-s-triazin-3(2H)-one; 5,6,7-trihydro- 5,7-(4-nitrodiphenyl)-thiazolo[3,2-b]-s-triazin-3(2H)-one; 5,6,7-trihydro-5,7-(2,2′-dinitrodiphenyl)-thiazolo[3,2-b]-s-triazin-3(2H)-one; 5,6,7-trihydro-5,7-(4,4′-dinitrodiphenyl)-thiazolo[3,2-b]-s-triazin-3 (2H)-one with their different percentages.     

Nitriles in heterocyclic synthesis. Part II: Synthesis and application of pyrano[3,2-h]quinoline sulphonamide derivatives

5-Sulphonamido-8-quinolinol reacts with cinnamonitrile derivatives in the presence of a basic catalyst to give pyrano[3,2-h]quinoline sulphonamide derivatives ( 8_a-d-13_a-d ). The reaction of 8_b, 9_b with some reagents such as acetic anhydride, acetic anhydride/pyridine mixture, formamide and formic acid/formamide mixture gave the fused heterotetracyclic systems pyrimido-[4′, 5′: 6, 5]pyrano[3, 2-h] quinoline sulphonamide derivatives. The structures of all newly synthesized compounds were confirmed by elemental analyses and spectral data. These compounds showed antimicrobial activity against some selected bacteria in vitro.     

One pot synthesis of novel thiazolo[3,2-b][1,2,4]triazoles: A useful synthetic application of the acidified acetic acid method

Thiazolo[3,2-b][1,2,4]triazoles and some of its analogues were firstly synthesized starting from 3-benzyl-1,2,4-triazole-5-thiol (13). 3-Benzyl-1,2,4-triazole-5-thiol (13) was synthesized and reacted with aromatic ketones using the acidified acetic acid method (AcOH/H⁺) to give directly the cyclized 5-aryl-2-benzyl-1,3-thiazolo[3,2-b][1,2,4]triazoles (15a-f) rather the thioketones 14. The isomeric 2-benzyl[2,3-c]-1,2,4-triazoles 16 could not be obtained using this method. The reaction of 1-phenylacetyl-3-thiosemicarbazide (17) with phenyl bromomethyl ketones in refluxing ethanol afforded the 2-(phenylacetyl-hydrazino)-4-phenylthiazole (18) which, cyclized into 16a upon refluxing in POCl₃. The tricyclic system 20a–d was successfully prepared in one pot reaction using the acidified acetic acid in high reaction yield and short reaction time. Formation of both 15a–l and or 16a–c was assigned by the molecular minimization energy (MME) calculations which indicated that the formation of 15 is more favorable than the isomeric compounds 16. Examination of the biological activity against the selected bacteria and fungi revealed that the title compounds possess significant growth promoting effect.     

A Novel and Expedient Approach to New Thiazoles, Thiazolo[3,2-a]pyridines, Dihydrothiophenes, and Hydrazones Incorporating Thieno[2,3-b]thiophene Moiety

This paper reports details about the synthesis of a series of novel functionalized symmetrical bis-heterocyclic compounds containing a thieno[2,3-b]thiophene motif. Bis-thiazole derivatives 2, 3a-c and thiazolo[3,2-a]pyridine derivatives 4a-c are achieved. The hitherto unknown dihydrothiophene derivatives 6a-dvia bis-pyridimium salt 5 are obtained. Additionally, the novel hydrazonothieno[2,3-b]thiophene derivatives 10a-c are obtained via bis-tosylacetylthieno[2,3-b]thiophene derivative 9. All compounds are characterized by (1)H-, (13)C-NMR, GCMS, IR, and UV-vis spectrometry. These compounds represent a new class of sulfur and nitrogen containing heterocycles that should also be of interest as new materials.     

Pyryliumverbindungen. 41. 7aH-Cyclopenta[b]pyran-7-one durch Ringtransformation von 2,4,6-Triaryl-pyryliumsalzen mit acyclischen 1,2-Diketonen

Pyrylium Compounds. 41. 7aH-Cyclopenta[b]pyran-7-ones by Ring Transformation of 2,4,6-Triarylpyrylium Salts with Acyclic 1,2-Diketones Reaction of 2,4,6-triarylpyrylium salts 1 with acyclic 1,2-diketones 2 (CH₃COCOR, R = Me, Ph) in the presence of an appropriate condensing agent (e.g. piperidine acetate, triethyl-amine/acetic acid, sodium acetate) yields the hitherto unknown 2,4,5,7a-substituted 7aH-cyclopenta[b]pyran-7-ones 3 as a result of a new type of ring transformation (2,5-[C₄O+C]/2,3-[C₂+C₃]). A characteristic feature of compounds 3 is their ability to undergo electrophilic substitutions. Thus, stepwise bromination of the 7a-methyl derivative 3a in acetic acid affords 6-bromo-7a-methyl-2,4,5-triphenyl-cyclopenta[b]pyran-7-one ( 4 ) and 3,6-dibromo-7a-methyl-2,4,5-triphenyl-cyclopenta[b]pyran-7-one ( 5 ); analogously, nitration of 3a leads to 7a-methyl-6-nitro-2,4,5-triphenyl-cyclopenta[b]pyran-7-one ( 6 ), indicating that position 6 is the favoured position for electrophilic substitutions. Contrary to the 3,5-unsubstituted pyrylium salts 1 , the 3,5-dimethyl-2,4,6-triphenyl-pyrylium perchlorate ( 13 ) reacts with 1,2-diketones 2 through a 2,6-[C₅+C] transformation to give arylsubstituted 1,2-diones 14 . The structure of the new compounds was determined by spectroscopic methods and by a single crystal X-ray analysis of the dibromo derivative 5 .     

Two-component,one-pot synthesis of pyrimido[1,2-b] [1,2,4,5]tetrazines

Derivatives containing the cyclohepta4′,5′thieno[2′,3′:4,5]pyrimido[1,2-b][1,2,4,5]-tetrazin-6-one system were prepared from the reaction of 3-amino-2-thioxo-1,2,3,5,6,7,8,9-octahydro-4H-cyclohepta[4,5]thieno[2,3-d]pyrimidin-4-one (5) or its 2-methylthio derivative 6 with hydrazonoyl chlorides 9. The mechanism of the studied reactions has been discussed and the biological activity of the isolated products has been evaluated.     

A facile synthesis of some novel fused [1,2,4]triazolo[3,4-b][1,3,4]thiadiazol derivatives

A series of novel 3-[6-(4-substituted phenyl)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol-3-ylmethyl]-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one derivatives (7a–7h) have been synthesized from 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carbonitrile (1) through a multi-step reaction sequence. The key intermediate (6) on condensation with various substituted aromatic carboxylic acids in the presence of phosphorus oxychloride afforded the series of title compounds (7a–7h). The structures of all newly synthesized compounds were established on the basis of their IR, ¹H-NMR, ¹³C-NMR and liquid chromatography mass spectrometry spectral data.     

Nitration of Condensed Polycyclic Aromatic Ketones

Nitration of three isomeric dibenzanthrones, 13H-dibenzo[a,de]-anthracene-13-one(3), 7H-benzo[hi]chrysene-7-one(4), and 7H-dibenzo[a,kl]anthracene-7-one(5), with concentrated nitric acid was studied under various conditions. The nitration of (3) at 15 °C in 1,1,2,2-tetrachloroethane gave the 5-nitro derivative. The nitration of (4) in boiling acetic acid produced the 9-nitro derivative. The nitration of (5) at 70 °C in acetic acid gave the 5-nitro derivative. These nitro compounds are very useful in synthesizing undecacyclic aromatic hydrocarbons.     

Chemistry of Substituted Quinolinones IV. Regioselective Nucleophilic Substitution of 1,3-Dichlorobenzo[f]quinoline

1,3-Dichlorobenzo[f]quinoline 2 was obtained from 1-hydroxybenzo[f]quinolin-3-one 1. Nucleophilic substitution, hydrolysis, hydrazinolysis and azidation reactions of compound 2 have been studied and found regioselective. Also, 1-aminobenzo[f]quinolinone 11 was obtained and used to prepare the benzoquinolinylthiourea derivative 12, naphthonaphthyridinedione 13, benzoquinolinylhydrazonoquinoline 15 and benzo[f]-quinolinyl enamine 17.     

Synthesis of some new fused thiopyrano[2,3-d]thiazoles and their derivatives

A series of some new fused thiopyrano[2,3-d]thiazole derivatives have been synthesized by a stereo-selective hetero-Diels-Alder reaction of 5-(2,4-dihydroxy-benzylidene)-4-thioxo-thiazolidine derivatives 3a,b with acrylonitrile, ethyl acrylate, N-phenylmale-imide, ω-nitrostyrene and N-phenyl-1, 3, 4-triazole-2,5-dione. 5-Amino-9-hydroxy-dihydro-benzopyrano[3′,4′:4,5]thiopyrano[2,3-d]thiazol-6-one derivatives 14a,b have been synthesized by Michael addition of 3a,b with malononitrile. Structures and conceivable mechanisms are discussed.     

An efficient microwave-assisted synthesis of thieno[2,3- b ]quinolines under solvent-free conditions

A novel and efficient method for the synthesis of substituted thieno[2,3-b]quinolines has been developed. A simple one-pot reaction of 3-formyl-2-mercaptoquinolines 2a–l with 1-chloroacetone, 2-chloroacetamide, ethyl chloroacetate and 2-chloro-1-phenylethanone in presence of catalytic amount of potassium carbonate under microwave irradiation and solvent-free conditions gave thieno[2,3-b]quinolin-2-ylethanone derivatives 3a–e, thieno[2,3-b]quinoline-2-carboxamide derivatives 4a–e, ethyl thieno[2,3-b]quinoline-2-carboxylate 5a–e and phenyl(thieno[2,3-b]quinolin-2-yl)methanone derivatives 6a–e compounds respectively. The structures of all the newly synthesised compounds were elucidated on the basis of elemental analysis, IR, ¹H NMR and mass spectral data.     

Pyridine-2(1H)-thione in heterocyclic synthesis: synthesis and antimicrobial activity of some new thio-substituted ethyl nicotinate,thieno[2,3-b]pyridine and pyridothienopyrimidine derivatives

3-(4-Bromophenyl)-2-cyanoprop-2-enethioamide (1) reacted with ethyl 3-oxo-3-phenylpropanoate (2) to give ethyl 4-(4-bromophenyl)-5-cyano-2-phenyl-6-thioxo-1,6-dihydropyridine-3-carboxylate (3). Compound 3 was taken as a starting material for the synthesis of thio-substituted ethyl nicotinate derivatives 5a–d, which underwent cyclization to the corresponding thieno[2,3-b]pyridines 6a–d. Also 3 reacted with hydrazine hydrate to give the pyrazolo[3,4-b]pyridine derivative 7, which upon diazotization gave the diazonium derivative 8. Compound 6a condensed with dimethylformamide–dimethylacetal to afford thieno[2,3-b]pyridine derivative 9, which reacted with different amines 10a–e to afford the pyridothienopyrimidine derivatives 12a–e through the Dimroth rearrangement. Moreover, compound 6a reacted with different reagents to give pyridothienopyrimidine derivatives 14a and b, 17 and pyrazolothienopyridine derivative 18. In addition, acetylating compound 6c with chloroacetylchloride afforded the 3-[(2)-chloroacetylamino]thieno[2,3-b]pyridine derivative 20, which upon cyclization yielded the corresponding 2-chloromethylpyrido[3′,2′:4,5]thieno[3,2-d]pyrimidine derivative 21. Some of the newly synthesized compounds were screened in vitro for their antimicrobial activities.

     

Die Nitril-Carboxamid-Umlagerung

The Nitrile Carboxamide Rearrangement By reaction of cyclohexanone-2-carboxamide ( 4 ) with cyan amide 1-cyano-cyclohex-1-en-2-yl-urea ( 6 ) is formed via nitrile carboxamide rearrangement. Whilst compound 6 with 1,2-diaminobenzene hydrochloride forms 11-amino-1 H-2,3,4,5-tetrahydrodibenzo[b,e][1,4]diazepin hydrochloride ( 8 and 8a ), compound 6 and 1,2-diaminobenzene form hexahydro-benzimidazo[1,2-c]-quinazolin-6-one ( 12 ). Compound 8 with sodium hydroxide yields 11-amino-1 H-2,3,4,11a-tetrahydrodibenzo[b,e]-[1,4]diazepin ( 9 ). Compound 6 reacts with cyclohexylamine to form N-(1-cyanocyclohex-1-en-2-yl)-N′-cyclohexyl urea ( 10 ). Compound 10 with 1,4- or 1,2-diaminobenzene hydrochloride yields compound 7 and 8 . In alkaline solution 10 cyclises to 4-amino-3-cyclohexyl-2,3,5,6,7,8-hexahydroquinazolin-2-one ( 11 ). Compound 4 and malonitrile form either 3-amino-4-cyano-1,2,5,6,7,8-hexahydro-isoquinol-1-one ( 13 ) or 1-amino-4-cyano-2,3,5,6,7,8-hexahydro-isoquinol-3-one ( 14 ). Compound 13 and alkaline formaldehyde react to cyanooctahydroisoquinoline-[2,3-c] [1,3,5]oxdiazin-6-one ( 17 ). 2-Cyanoethyl-cyclohexan-one-2-carboxamide ( 22 ), prepared by Michael-reaction from 4 and acrylonitrile, forms via nitrile carboxamide rearrangement 10-cyano-1,2,3,4,5,6,7,10-octahydroquinolin-2-one ( 24 ) and 2-(1′-cyano-cyclohexyl-2′-one)-propionic acid ( 25 ). Nucleophilic attack of the NH₂-group at the cyanogroup of compound 22 forms 5-(spirocyclohexan-2′-one)-hexahydropyridin-2,6-dione ( 27 ).     

Synthesis and Dyeing Examinations of 7H, 9H-Quinazolino [3,2-b] benz [d,e] isoquinolin-7-one

The synthesis and application of a representative compound of the new group of disperse dyes derived from 7H,9H-quinazolino[3,2-b] benz[d, e] isoquinolin-7-one (II) have been investigated. The MS, IR and NMR spectra of compound (II) are analysed, and its dyeing and colour properties are compared with 7H-benzimidazo-[2,1-a] benz [d.e] isoquinolin-7-one (I).     

Reactions with Thiazolo[3,2-b]-s-triazol-3(2H)-ones

5-Aryl-3-carboxymethylthio-1,2,4-triazoles 2 are cyclised to 6-arylthiazolo[3,2-b]-s-triazol-3(2H)-ones 3 . This structural assignment has been based on IR and NMR spectra. 2-Arylmethylene-6-arylthiazolo[3,2-b]-s-triazol-3(2H)-ones 7 were prepared by several methods. Compounds 3 coupled with diazotised anilines to give 2,3-dihydro-6-arylthiazolo[3,2-b]-s-triazole-2,3-dione 2-arylhydrazones 8 . The action of amines on 3a opens the thiazolone ring with the formation of substituted (5-phenyltriazol-3-ylthio)-acetamides 9 .     

Hydrothermal Syntheses and Crystal Structures of Two Coordination Polymers with Terephthalic Acid and N-Donor Ligand: 2-Methyldipyrido[3,2-f:2′,3′-h]quinoxaline

Two 3D coordination polymers, [Cd(BDC)(Medpq)·H₂O]_n 1, and [Co(BDC)(Medpq)·H₂O] _n 2 (BDC = terephthalic acid, Medpq = 2-Methyldipyrido[3,2-f:2′,3′-h]quinoxaline), have been synthesized by self-assembly. The structure analyses show that both of the two coordination polymers are formed by 1D infinite chains through non-covalent interactions, and both of them are based on 1D zigzag ones. The photoluminescent study of the coordination polymer [Cd(BDC)(Medpq)·H₂O] _n shows that it exhibit fluorescent emission bands at 567.7 nm.     

Novel Thienopyridines

A number of novel thieno[2,3-b]pyridines were prepared from the reaction of 1 with unsaturated haloalkanes, and by the reaction of the amino ketones 9 and 10 with DMF dimethylacetal or triethyl orthoformate. The synthesis of novel thieno[2,3-c] and [3,2-c] pyridines, and a thieno[2,3-b;4,5-b']dipyridine are also reported.     

Synthesis, photoluminescence, and theoretical studies of novel Cu(I) complex

A novel diimine Cu(I) complex [Cu(ABPQ)(DPEphos)]BF₄ [ABPQ and DPEphos are acenaphtho[1,2-b]bipyrido[2,3-h;3,2-f]quinoxaline and bis(2-(diphenylphosphanyl)phenyl) ether, respectively] is synthesized, and its photophysical properties are experimentally and theoretically characterized. The emission bands centered at ca. 400/470 and 550 nm of [Cu(ABPQ)(DPEphos)]BF₄ are attributed to the ligand-centered π → π* transition and the metal-to-ligand charge transfer dπ(Cu) → π*(N–N) transition, respectively. The luminescence quantum yield of [Cu(ABPQ)(DPEphos)]BF₄ in CHCl₃ is found to be about five times higher than that of [Cu(Phen)(DPEphos)]BF₄.