Chloroform → methyl 11-methyl-6H-pyrido[4,3-b]carbazole-5-carboxylate

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Reaction Steps

To a solution of 200 mg (13 mmol) of metallic sodium in 600 mL of dry MeOH there were added 2.70 g (5.3 mmol) of the quaternary salt 22, 1.06 g (6.3 mmol) of p-nitrosodimethylaniline, and 300 mL of dry CHCl3. The suspension was stirred overnight at room temperature in a nitrogen atmosphere and then evaporated to dryness. The residue was suspended in a solution of 30 mL of CHCl3 and 5 mL of MeOH and flash chromatographed on a column of 40 g of silica gel with ether-triethylamine (20:1) as the eluant. The purest fraction was set aside and the less pure material was rechromatographed. The process was repeated, and the purest fractions which showed essentially only one spot on TLC were combined; wt 715 mg (47%). After crystallization from EtOAc-CH2Cl2 (5:1), the yellow needles melted at 203°-204° C. dec: NMR (Me2SO-d6) 11.56 (s, 1 H), 9.73 (s, 1 H), 8.87 (d, 1 H), 8.53 (d, 1 H), 8.38 (d, 1 H), 7.80 (d, 1 H), 7.60-7.52 (m, 1 H), 7.30-7.29 (m, 1 H), 4.10 (s, 3 H), 3.33 (s, 3 H); IR (KBr) 3300, 2950, 1675, 1600, 1465 cm-1.

Provenance & Evidence