- About this Journal
- Abstracting and Indexing
- Aims and Scope
- Article Processing Charges
- Articles in Press
- Author Guidelines
- Bibliographic Information
- Citations to this Journal
- Contact Information
- Editorial Board
- Editorial Workflow
- Free eTOC Alerts
- Publication Ethics
- Reviewers Acknowledgment
- Submit a Manuscript
- Subscription Information
- Table of Contents
Journal of Chemistry
Volume 2013 (2013), Article ID 851297, 13 pages
2-Chloroquinoline-3-carbaldehyde II: Synthesis, Reactions, and Applications
1Applied Organic Chemistry Department, National Research Centre, Dokki, Giza 12622, Egypt
2Shaqra University, Dawadami, Saudi Arabia
3Chemical Industries Division, National Research Centre, Dokki, Giza 12622, Egypt
4Chemistry Department, Faculty of Science, Jazan University, Saudi Arabia
Received 13 May 2013; Accepted 17 September 2013
Academic Editor: Patricia Valentao
Copyright © 2013 Bakr F. Abdel-Wahab and Rizk E. Khidre. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
This review deals with synthesis and reactions of 2-chloroquinoline-3-carbaldehyde during the period from 1979 to 1999. The reactions are subdivided in groups that cover the reactions of chloro- and aldehyde substituent as well as reactions which involve both groups. Some of these reactions have been applied successfully to synthesis of biologically important compounds. The main purpose of this review is to present a survey of the literature on 2-chloroquinoline-3-carbaldehyde chemistry and provide useful and up-to-date data for organic and medicinal chemist since such compound has not been previously reviewed in this period.
Over the past two decades, 2-chloroquinoline-3-carbaldehydes and their derivatives have attracted much attention due to their considerable biological and pharmacological activities as antimicrobial [1–7], anti-inflammatory [8, 9], antimalarial , and antivirus activities . Despite this versatile importance and in continuation of our previous review articles [12–16], 2-chloroquinoline-3-carbaldehydes have not been previously reviewed in the period from 1979 to 1999. The present review aims to complete our review article about these compounds .
2. Synthetic Methods
2.1. Vilsmeier-Haack Reaction
It was reported that one-pot synthesis of pyrido[2,3-b]quinolin-2-ones 2 in moderate yields (22–59%) was archived by treatment of substituted acetanilide with DMF and POCl3, to produce compound 1; to this reaction mixture a secondary amide was added in POC13 solution containing one drop of DMF, and the mixture was heated for a further 2-3 h at 75°C (Scheme 2) .
3. Chemical Reactions
3.1. Substitution Reactions
3-Formylquinoline-2(1H)-thione (X = S) and -seleno I (X = Se) 3 have been prepared from reaction of 1 with NaXH (X = S, Se). Compounds 3 reacted with primary amine to produce Schiff’s bases 4 (Scheme 3) .
Treatment of 2-(3-(1,3-dioxolan-2-yl)quinolin-2-yl)-N-substituted hydrazinecarbothioamide 7, which is prepared by two steps: first reaction of 1 with ethylene glycol followed by reaction with hydrazine hydrate to afford 3-(1,3-dioxolan-2-yl)-2-hydrazinoquinoline 6. The latter compound reacted with substituted isothiocyanates and with α-halocarbonyl compounds which yielded thiazolidinone 8 and thiazoline derivatives 9. The antimicrobial and inotropic and chronotropic activities of the prepared compounds were studied (Scheme 4) .
Cyclization of compound 1 with CS2 in EtOH/NaOH or pyridine gave the triazolo[4,3-a]quinoline-1-thione 10. Treatment of 10 with 60% HCO2H gave the corresponding aldehyde 11. [1,2,4]Triazolo[4,3-a] quinolines 15a–c were prepared and screened as antimicrobial, inotropic, and chromotropic agents. Thus, reaction of 2-hydrazino-3-(1,3-dioxolan-2-yl)quinoline 6 with aromatic aldehyde or benzoyl chloride followed by fusion in presence of air underwent cyclodehydrogenation to give the target compounds. The latter compounds were also prepared directly from reaction of compound 1 with aldehyde by fusion (Scheme 5) .
Reaction of compound 1 with acetic acid at reflux temperature leads to formation of quinolone 16 which was condensed with ethyl bromoacetate to give ethyl 6-methylfuro[2,3-b]quinoline-2-carboxylate 17 (Scheme 6) .
2H-Pyrano[2,3-b]quinolin-2-ones 20 were prepared in 46–95% by treating compound 1 with HCl to give quinolones 18, which reacted with malonic acid in ethanol in the presence of pyridine and piperidine followed by cyclization in polyphosphoric acid . In a similar manner the related cyanoacrylic acid and its ethyl ester 21 both gave pyranoquinoline-3-carboxylic acid 22 in 90% yield on treatment with PPA (Scheme 7) .
Compounds 1 reacted with alkylthiol to afford 2-(alkylthiol)quinoline-3-carbaldehydes 31. In an alternate method compound 31 was also obtained by the reaction of 2-mercaptoquinoline-3-carbaldehyde with ally1 bromide. Allyl thioethers 31 were converted into oximes by reaction with hydroxylamine hydrochloride in the presence of aqueous sodium bicarbonate. Oximes were then oxidized with aqueous NaOCl to give nitrile oxides, which cyclize spontaneously to dihydro-3H-[1,2]oxazolo[3′,4′:4,5]thiopyrano[2,3-b] quinolone 34 in 81–86% yield. The oxidation was also carried out employing chloramine-T and mercuric acetate (Scheme 9) .
Treatment of compound 1 with sodium iodide in acetonitrile followed by reduction with sodium borohydride to afford 2-iodoquinoline 35. Next, Pd(0)-mediated cross-coupling of the latter compound and 2-tributylstannyl acrylic acid, prepared in 95% yield by Pd(0)-promoted hydrostannylation of propiolic acid, provided compound 36 in 61% yield. Exposure of 36 to diphenyl phosphorazidate (DPPA) afforded the acyl azide 37 in an unoptimized 31% isolated yield. Cyclocondensation of azide 37 with 1-(1-cyclohexenyl)pyrrolidine yielded camptothecin 39 via the formation of intermediate enamine 38 (Scheme 10) .
3.2. Addition Reaction on Aldehyde Group
Reaction between compound 1 and acetone in the presence of piperidine and acetic acid gave 4-(2-chloroquinoline-3-yl)-4-hydroxybutan-2-one 44 accompanied with a small amount of chalcone. Reduction of β-keto alcohols 44 with sodium borohydride yielded the diastereoisomer 1,3-diols 45a,b in 64–92% yield. The intramolecular cyclization of 1,3-diols was performed in DMF containing HCl to produce (2R,4S) 46a and (2S,4S)-2,4-dimethyl-3,4-dihydro-2H-pyrano[2,3-b]quinoline 46b (Scheme 13) .
Mg-Al hydrotalcite catalyzes the reaction between compound 1 and nitromethane very efficiently to afford threo (1S,2R)-1-(2-chloroquinoline-3-yl)-2-nitropropane-1-ol 47a . On the other hand, it was reported synthesis of 1-(2-chloroquinoline-3-yl)-2-nitroethanol 47b and 2-chloro-3-(2-nitrovinyl)quinoline 48 from reaction of 1 with nitromethane (Scheme 14) . The synthesized compounds were tested in vitro for their antimycotic activity against Aspergillus fumigatus, Trichophyton mentagrophytes, Microsporum Gypseum, Epidermophyton floccosum and Candida albicans .
Grignard reaction of compound 1 with either MeMgI or PhMgI followed by oxidation using pyridinium chlorochromate gave 3-acetyl-2-chloroquinolines 49 . Methyl thieno[2,3-b]quinoline-2-carboxylates 51 were prepared in 70–80% yield by reaction of ketone 49 with methyl 2-mercaptoacetate in DMF containing anhydrous K2CO3 followed by cyclization in methanol containing piperidine. Compounds 49 were condensed with aromatic aldehyde to give the corresponding chalcones 52. The latter compounds were cyclocondensed with hydrazine to produce pyrazoles 53 (Scheme 15) .
Reduction of compound 1 followed by treatment with phospours tribromide and salicylaldehyde yielded chromeno[4,3-b]quinoline-4-carbaldehyde 54 which was reduced by Pd-C in methanol to produce 3-(3-(hydroxymethyl)quinolin-2-yl)benzaldehyde 55 (Scheme 16) .
Reaction of 4-amino-5-aryl-4H-1,2,4-triazole-3-thiols 56 with 1 was carried out without solvent using inorganic solid supports (e.g., silica or alumina) either in microwave irradiation [1, 2] or in DMF containing potassium carbonate  to give the triazolothiadiazole 57. The synthesized quinoline derivatives have been assessed for their anti-inflammatory, antibacterial, and antifungal activities (Scheme 17) .
3.3. Oxidation of Aldehyde Group
Oxidation of compound 1 with alkaline silver nitrate in ethanol gave the corresponding acid 53 in 73–75% yields. 2-Chloroquinoline-3-carboxylic acids 58 reacted with either o-phenylenediamine or 4,5-dichloro o-phenylenediamine in xylene to afford quino[2,3-b][1,5]benzodiazepine-12-ones 54 in 39–72% yield. In contrast the reaction of those acids 58 with 4,5-dimethyl o-phenylenediamine yielded benzimidazoles 60 in 60–70% yield (Scheme 18) .
3.4. Condensation Reactions
3.4.1. Reactions with Active Methylene Compounds
Compound 1 was condensed with either acetylacetone or ethyl cyanoacetate to give compounds 61 and 62, respectively . Methyl thieno[2,3-b]quinoline-2-carboxylates 63 were prepared in 70–80% yield by cyclocondensation of compound 1 with methyl 2-mercaptoacetate in DMF containing anhydrous K2CO3 (Scheme 19) .
Cyclization of chalcones 65 with hydrazine, phenylhydrazine, or thiourea to yield pyrazolylquinolines 61 and quinolinylpyrimidine-2-thione 62, respectively, was reported. The anti-inflammatory activity of the prepared compounds was studied (Scheme 21) .
Treatment of compound 1 with acetic anhydride and sodium acetate afforded the corresponding 2-oxopyrano[2,3-b]quinolines 72. Compounds were subjected to ammonia to yield the corresponding naphthyridines 73. The synthesized compounds were tested for their antimalarial, diuretic, clastogenic, and antimicrobial properties (Scheme 22) .
Cyclization of chloro(cyanovinyl)quinolines 74, prepared from condensation of 1 with 2-(4-chlorophenyl)acetonitrile, with secondary amines (e.g., piperidine, morpholine, and 4-methyl-1-piperazine), gave substituted benzonaphthyridines 75 in 34–98% yield (Scheme 23) .
3.4.2. Reactions with Hydrazine, Hydroxylamine, Hydrazides, (Thio)Semicarbazide, and (Thio)Urea
Reaction of compound 1 with phenyl hydrazine yielded 1-phenyl-1H-pyrazolo [3,4-b] quinoline 77 [7, 17, 38], whereas interaction with hydroxylamine hydrochloride afforded isoxazole[5,4-b]quinolines 78. Compounds 1 reacted with o-phenylenediamine and ethylenediamine in a 2 : 1 molar ratio to afford N,N′-bis-(2-chloroquinoline-3-yl-methylene)-o-phenylenediamines 79a and N,N′-bis-(2-chloroquinoline-3-yl-methylene)-ethylenediamines 79b, respectively. Pyrimido[4,5-b]quinolin-2-ol 80a and pyrimido[4,5-b]quinoline-2-thiol 80b were synthesized from reaction of compound 1 with urea and thiourea, respectively (Scheme 25) .
Preparation of pyrazolo[3,4-b]quinolines 83 as antiviral agents was reported by treatment of compound 1 with hydroxylamine in EtOH to give oxime 81. Stirring a solution of 81 and SOCl2 in DMF at 0°C yielded nitrile 82 which was refluxed with hydrazine in EtOH to give target compounds, which showed MIC of 1.5 μg/mL against herpes simplex virus type 2 and vasodilator activity with an EC50 of 31 Mm (Scheme 26) .
Wright and EP reported convenient synthesis of 3-(1H-tetrazol-5-yl)quinolin-2(1H)-one 85 from the reaction of 1 with a mixture of formic acid, hydroxylamine hydrochloride, and sodium formate at reflux temperature to give 3-cyano-2(1H)-quinolinone 84 followed by treatment of the latter compound with sodium azide and ammonium chloride . On the other hand 4-(1H-tetrazol-5-yl)tetrazolo[1,5-a]quinoline 86 was synthesized by the same author from treating 2-chloroquinoline-3-carbonitrile 82 with sodium azide and ammonium chloride at reflux temperature (Scheme 27) .
2-Chloro-3-cyanoquinoline 82, which was prepared from compound 1,  reacted with hydroxylamine to give amidoxime 87 which on ring closure in DMF containing potassium carbonate yielded isoxazoloquinoline 88 in 32% yield. Reaction of 82 with thiourea furnished 89 which were subjected to ring closure by reacting with chloroacetonitrile in DMF in the presence of potassium carbonate to yield 90 (Scheme 28) .
Benzo[b]quinolino[3,2-f][1,4]thiazepines 91a , and benzo[b]quinolino[3,2-f][1,4]oxazepines 91b  were synthesized from reaction of compound 1 with 2-aminothiophenol and 2-aminophenol, respectively. On the other hand, quinobenzodiazepine 92, dihydroquinobenzodiazepine 93, and benzimidazolyl quinoline 94 were prepared from reaction of compound 1 with o-phenylenediamine via oxidation intermediate benzimidazole quinolone to benzimidazolyl quinoline with simultaneous reduction of quinobenzodiazepine 92 to dihydroquinobenzodiazepine 93 (Scheme 29) .
Quinolinecarbaldehyde hydrazones 99 were prepared either by condensation of compound 1 with substituted hydrazinecarbothioamides or by addition of hydrazones 98 to phenyeleisothiocyanate. Cyclocondensation of 2-((2-chloroquinoline-3-yl)methylene)-N-arylhydrazinecarbothioamide 99 with substituted phenacyl bromide gave thiazoles 100. Compounds 99 and 100 were tested against Gram-positive and Gram-negative bacteria (Scheme 31) .
2-Chloroquinoline-3-carbaldehydes are easily available and have high chemical reactivity due to the presence of two active moieties chloro- and aldehyde functions. This survey attempts to summarize the synthetic methods and reactions of 2-chloroquinoline-3-carbaldehydes from 1979 to 1999.
- S. Paul and R. Gupta, “A simple and fast reaction of 3-substituted-4-amino-5-mercapto-s-triazoles with substituted aldehydes without solvent under microwave irradiation: an environment co-friendly synthesis,” Indian Journal of Chemical Technology, vol. 5, pp. 263–266, 1998.
- R. Gupta, S. Paul, P. Kamotra, and A. K. Gupta, “Rapid synthesis of s-triazolo [3,4-b] [1,3,4] thiadiazoles and quinolines under microwave irradiation,” Indian Journal of Heterocyclic Chemistry, vol. 7, no. 2, pp. 155–156, 1997.
- A. M. Farghaly, N. S. Habib, M. A. Khalil, and O. A. El-Sayed, “Synthesis of novel 2-substituted quinoline derivatives: antimicrobial, inotropic, and chronotropic activities,” Archiv der Pharmazie, vol. 323, no. 4, pp. 247–251, 1990.
- A. M. Farghally, N. S. Habib, A. A. B. Hazzaa, and O. A. El-Sayed, “Synthesis of substituted quinoline-3-carbaldehyde (2,3- dihydrothiazol-2-ylidene) hydrazones of potential antimicrobial activity,” Journal de Pharmacie de Belgique, vol. 40, no. 6, pp. 366–372, 1985.
- R. Gupta, A. K. Gupta, S. Paul, and P. L. Kachroo, “Synthesis and biological activities of some 2-chloro-6/8-substituted-3-(3-alkyl/aryl-5,6-dihydro-s-triazolo[3,4-b][1,3,4]thiadiazol-6-yl)quinolines,” Indian Journal Of Chemistry B, vol. 37, pp. 1211–1213, 1998.
- V. J. Bulbule, V. H. Deshpande, S. Velu, A. Sudalai, S. Sivasankar, and V. T. Sathe, “Heterogeneous henry reaction of aldehydes: diastereoselective synthesis of nitroalcohol derivatives over Mg-Al hydrotalcites,” Tetrahedron, vol. 55, no. 30, pp. 9325–9332, 1999.
- Z. Cziaky, F. Korodi, L. Frank, and I. Czink, “Synthesis and antimycotic activity of new 2-chloro-3-(2-nitro)ethyl- and (2-nitro)vlnylquinolines,” Heterocyclic Communications, vol. 2, no. 1, pp. 63–70, 1996.
- F. Herencia, M. L. Ferrándiz, A. Ubeda et al., “Synthesis and anti-inflammatory activity of chalcone derivatives,” Bioorganic and Medicinal Chemistry Letters, vol. 8, no. 10, pp. 1169–1174, 1998.
- O. A. El-Sayed, M. El-Semary, and M. A. Khalil, “Non-steroidal anti-inflammatory agents: synthesis of pyrazolyl pyrazolinyl and pyrimidinyl derivatives of quinolone,” Alexandria Journal of Pharmaceutical Sciences, vol. 10, no. 1, pp. 43–46, 1996.
- M. Sekar and K. J. R. Prasad, “Synthesis of some novel 2-oxopyrano[2,3-b]- and 2-oxopyrido[2,3-b]quinoline derivatives as potential antimalarial, diuretic, clastogenic and antimicrobial agents,” Journal of Chemical Technology and Biotechnology, vol. 72, pp. 50–54, 1998.
- M. R. Bell and J. H. U. S. Ackerman, US, 4920128, 1990, http://worldwide.espacenet.com/numberSearch?locale=en_EP.
- B. F. Abdel-Wahab, R. E. Khidre, and A. A. Farahat, “Pyrazole-3(4)-carbaldehyde: synthesis, reactions and biological activity,” Arkivoc, vol. 2011, no. 1, pp. 196–245, 2011.
- W. M. Abdou and R. E. Khidre, “Overview of the chemical reactivity of phosphonyl carbanions toward some carbon-nitrogen systems,” Current Organic Chemistry, vol. 16, no. 7, pp. 913–930, 2012.
- B. F. Abdel-Wahab, R. E. Khidre, A. A. Farahat, and A. A. S. El-Ahl, “2-Chloroquinoline-3-carbaldehydes: synthesis, reactions and applications,” Arkivoc, pp. 211–276, 2012.
- R. E. Khidre and B. F. Abdel-Wahab, “Application of benzoylaceteonitrile in the synthesis of pyridines derivatives,” Current Organic Chemistry, vol. 17, no. 4, pp. 430–445, 2013.
- R. E. Khidre, H. A. Mohamed, and B. F. Abdel-wahab, “Synthesis of 5-membered heterocycles using benzoylacetonitriles as synthon,” Turkish Journal of Chemistry, vol. 37, pp. 1–35, 2013.
- M. Kidwai and N. Negi, “Synthesis of some novel substituted quinolines as potent analgesic agents,” Monatshefte fur Chemie, vol. 128, no. 1, pp. 85–89, 1997.
- O. Meth-Cohn, B. Narine, B. Tarnowski et al., “A versatile new synthesis of quinolines and related fused pyridines—part 9: synthetic application of the 2-chloroquinoline-3-carbaldehydes,” Journal of the Chemical Society, Perkin Transactions 1, vol. 9, pp. 2509–2517, 1981.
- O. Meth-Cohn, B. Narine, and B. Tarnowski, “A versatile new synthesis of quinolines and related fused pyridines—part 5: the synthesis of 2-chloroquinoline-3-carbaldehydes,” Journal of the Chemical Society, Perkin Transactions 1, vol. 5, pp. 1520–1530, 1981.
- J. H. Rigby and D. M. Danca, “Vinyl isocyanates in alkaloid synthesis. Camptothecin model studies,” Tetrahedron Letters, vol. 38, no. 28, pp. 4969–4972, 1997.
- Wright and T. L. EP, 120483, 1984, http://worldwide.espacenet.com/numberSearch?locale=en_EP.
- O. Meth-Cohn and B. Tarnowski, “A versatile new synthesis of quinolines and related fused pyridines—part IV: 1 A simple one-pot route to pyrido[2,3-b]quinolin-2-ones from anilides,” Tetrahedron Letters, vol. 21, no. 38, pp. 3721–3722, 1980.
- L. E. Konstantinovskii, R. Y. Olekhnovitch, M. S. Korobov, L. E. Nivorozhkin, and V. I. Minkin, “Stereodynamical interconversion of bis(N-aryl-α-isopropyl-β-aminovinylthionato)zinc(II) and -cadmium(II),” Polyhedron, vol. 10, no. 8, pp. 771–778, 1991.
- M. A. Khalil, N. S. Habib, A. M. Farghaly, and O. A. El-Sayed, “Synthesis, antimicrobial, inotropic, and chronotropic activities of novel 1,2,4-triazolo[4,3-a]quinolines,” Archiv der Pharmazie, vol. 324, no. 4, pp. 249–253, 1991.
- T. Tilakraj and S. Y. J. Ambekar, “Synthesis and mass spectra of some 2H-pyrano[2,3-b]quinolin-2-ones,” Indian Journal of Chemistry, vol. 62, pp. 251–253, 1985.
- R. A. Pawar, P. B. Bajare, and S. B. Mundade, “Studies on Vilsmeier-Haack reaction. A new route to 2-chloroquinoline-3-carboxyaldehydes an a furoquinoline derivative,” Journal of the Indian Chemical Society, vol. 67, no. 8, pp. 685–686, 1990.
- B. Prabhuswamy and S. Y. Ambekar, “Synthetic communications: an international journal for rapid communication of synthetic organic chemistry,” Synthetic Communications, vol. 29, no. 20, pp. 3477–3485, 1999.
- Z. Cziaky and F. Korodi, “A new heterocyclic ring system: 13H-Benzimidazo[2′,1′:2,3][1,3]thiazino[6,5-b]quinoline,” Heterocycles, vol. 36, pp. 2475–2482, 1993.
- F. Korodi, Z. Cziaky, and Z. Szabo, “Fused 1,2,4-triazole heterocycles. I. Synthesis of novel [1,2,4]triazolo[5’,1’:2,3][1,3]thiazino[6,5-b]quinolines,” Heterocycles, vol. 34, no. 9, pp. 1711–1720, 1992.
- Z. Cziaky and Z. Szabo, “Synthesis of 2H-pyrano[2,3-b]quinolines—part II: preparation and 1H-nmr investigations of 4-hydroxy-2-methyl-3,4-dihydro-2H-pyrano[2,3-b]quinolines,” Journal of Heterocyclic Chemistry, vol. 32, pp. 755–760, 1995.
- B. B. Neelima and A. P. Bhaduri, “Novel synthesis of isoxazolo[5,4-b]quinolines,” Journal of Heterocyclic Chemistry, vol. 21, p. 1469, 1984.
- B. Bhat and A. P. Bhaduri, “A novel one-step synthesis of 2-methoxycarbonylthieno[2,3-b]quinolines and 3-hydroxy-2-methoxycarbonyl-2,3-dihydrothieno[2,3-b]-quinolines,” Synthesis, vol. 1984, no. 8, pp. 673–676, 1984.
- R. P. Srivastava, Neelima, and A. P. Bhaduri, “Synthetic applications of 2-chloro-3-formylquinoline,” Journal of Heterocyclic Chemistry, vol. 24, pp. 219–222, 1987.
- K. R. Rao, N. Bhanumathi, and P. B. Sattur, “Synthesis of novel quino[2,3-b][1,5]benzodiazepin-12-ones,” Journal of Heterocyclic Chemistry, vol. 28, pp. 1339–1340, 1991.
- R. P. Srivastava, Neelima, and A. P. Bhaduri, “Reactions of 2-chloro-3-formylquinolines,” Indian Journal of Chemistry B, vol. 26, pp. 418–422, 1987.
- R. P. Srivastava, Neelima, and A. P. Bhaduri, “A convenient synthesis of 2,3-disubstituted benzo[b][1,8]naphthyridines; a novel annelation reaction of 2,3-disubstituted quinolines,” Synthesis, vol. 5, pp. 512–514, 1987.
- G. R. Rao and K. S. Rao, “Synthesis and biological activity of quino[3,2-f]-1,2,4-triazolo[3,4-b]thiadiazepines: a novel tetracyclic ring system,” Indian Journal of Pharmaceutical Sciences, vol. 53, pp. 37–39, 1991.
- A. M. Farghaly, N. S. Habib, A. A. B. Hazzaa, and O. A. El-Sayed, “A convenient novel method for the synthesis of 1H-pyrazolo[3,4-b]quinoline and its derivatives,” Alexandria Journal of Pharmaceutical Sciences, vol. 3, pp. 84–86, 1989.
- Wright and T. L. EP, 120484, 1984, http://worldwide.espacenet.com/numberSearch?locale=en_EP.
- B. B. Neelima and A. P. Bhaduri, “Reactions of 2-chloro-3-formylquinolines,” Indian Journal of Chemistry B, vol. 23, p. 431, 1984.
- I. Torrini, G. P. Zecchini, and M. P. Paradisi, “The condensation products of 2-chloro-3-formylquinolines with o-aminothiophenol,” Heterocycles, vol. 27, no. 2, pp. 401–405, 1988.
- G. P. Zecchini, I. Torrini, and M. P. Paradisi, “Synthesis of quino/2,3-b_//1,5/benzoxazepines: a novel tetracyclic ring system,” Heterocycles, vol. 26, no. 9, pp. 2443–2447, 1987.
- N. Bhanumathi, K. R. Rao, and P. B. Sattur, “Novel formation of 11,12-dihydro-6H-quino[2,3-b] [1,5] benzodiazepines: reaction of 2-chloroquinoline-3-carbaldehydes with o-phenylenediamine,” Heterocycles, vol. 24, no. 6, pp. 1683–1685, 1986.
- K. R. Prasad and M. Darbarwar, “Synthesis of benzopyrano[3,4-h]benzo[b]-1,6-naphthyridine-6-ones,” Organic Preparations and Procedures International, vol. 27, no. 5, pp. 547–550, 1995.