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Synlett 2011(1): 116-120  
DOI: 10.1055/s-0030-1259097
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Regioselective Synthesis of Annulated Quinoline and Pyridine Derivatives by Silver-Catalyzed 6-endo-dig Cycloisomerization

K. C. Majumdar*, Raj Kumar Nandi, Sintu Ganai, Abu Taher
Department of Chemistry, University of Kalyani, Kalyani 741235, West Bengal, India
e-Mail: kcm_ku@yahoo.co.in;
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Publication History

Received 29 September 2010
Publication Date:
10 December 2010 (online)

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Abstract

3H-pyrano[3,2-f]quinoline-3-one, 4-methyl-4,7-phen­anthrolin-3(4H)-one, and 1,3-dimethylpyrido[3,2-d]pyrimidine-2,4(1H,3H)-dione derivatives have been synthesized by hitherto unreported silver-catalyzed 6-endo-dig mode of cycloisomerization from various N-propargylated heterocyclic compounds. The silver-catalyzed reaction provides the synthesis of potential bioactive compounds in excellent yields.

Key words

3H-pyrano[3,2-f]quinoline-3-one - 4-methyl-4,7-phen­anthrolin-3(4H)-one - 1,3-dimethylpyrido[3,2-d]pyrimidine-2,4(1H,3H)-dione - AgSbF6 - cycloisomerization - 6-endo-dig

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Synthesis of 4,10-Dimethyl-4,7-phenanthrolin-3 (4 H )-one (4d) To a stirred solution of AgSbF6 (7.6 mg, 0.022 mmol) in DMSO (5 mL), 6-(but-2-ynylamino)-1-methylquinolin-2 (1H)-one (3d, 50 mg, 0.22 mmol) was added at r.t. and stirred at 110 ˚C for 45 min to complete the reaction (as monitored by TLC). The light green colored reaction mixture was cooled and neutralized with sat. NaHCO3 solution. This was extracted with CH2Cl2 (3 × 15 mL). The combined organic extract was washed with brine and dried over (Na2SO4). The solvent was distilled off. The resulting crude product was purified by column chromatography over silica gel (60-120 mesh) using PE-EtOAc mixture (3:2) as an eluent to give the product 4d. Yield 96%, yellow solid, mp 172 ˚C. IR (KBr): 1646, 1561 cm-¹. ¹H NMR (400 MHz, CDCl3): δ = 3.00 (s, 3 H, CH3), 3.88 (s, 3 H, NCH3), 6.81 (d, 1 H, J = 10.0 Hz, C3H of quinolone), 7.34 (d, 1 H, J = 4.4 Hz, ArH), 7.77 (d, 1 H, J = 9.6 Hz, ArH), 8.22 (d, 1 H, J = 9.2 Hz, ArH), 8.72 (d, 2 H, J = 10.0 Hz, C4H of quinolone and ArH). ¹³C NMR (100 MHz, CDCl3): δ = 26.4, 30.6, 115.6, 117.9, 119.7, 125.8, 126.5, 134.2, 136.9, 140.4, 143.3, 145.4, 148.6, 161.5. HRMS: m/z calcd for C14H12N2O [M + H]: 225.1016; found: 225.1022.