HCID 21072277, compound → HCID 21072274, compound

Participants

Reaction Steps

To a mixture of 6-bromo-9-tert-butoxycarbonyl-3-methyl-1,2,3,4-tetrahydrocarbazole obtained in Example 24 (2.0 g, 5.49 mmol), 2,3-dichloro-4,5-dicyano-1,4-benzoquinone (2.62 g, 11.5 mmol) and activated 3 Å molecular sieves was added anhydrous benzene (17 mL) under a nitrogen atmosphere, and the mixture was refluxed for 20 h. The cooled reaction mixture was filtered and the filtrate evaporated. The crude product was chromatographed (PS with gradient elution up to PS:DCM 3:1) to afford 3-bromo-9-tert-butoxycarbonyl-6-methylcarbazole (1.64 g, 4.56 mmol, 83%) as a colourless solid. By-products were also obtained—6-bromo-9-tert-butoxycarbonyl-4-ethoxy-3-methylcarbazole (12 mg, 0.030 mmol, 0.5%) was obtained as a colourless oil, and 6-bromo-9-tert-butoxycarbonyl-1,2-dihydro-3-methylcarbazol-4-(3H)-one (52 mg, 0.14 mmol, 2.5%) was obtained as a pale yellow solid.

Provenance & Evidence