Hydrochloric Acid → 9-Acetyl-8-methoxy-1,2-dihydro-6-(3-dimethylaminopropyl)-cyclopenta[c]carbazole-3-one

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Reaction Steps

NaH (6.88 g of 60%, 171.95 mmol, 2.5 eq) was added to a suspension of 9-acetyl-8-methoxy-1,2-dihydro-6H-cyclopenta[c]carbazole-3-one (83) (26 g, 68.78 mmol, 1 eq) in dry CH2Cl2 (300 mL), and the mixture was stirred at room temperature for 20-30 min until the evolution of hydrogen ceased. 3-Dimethylaminopropylchloride hydrochloride (16.3 g, 103.16 mmol, 1.5 eq) was added portionwise under nitrogen. The reaction mixture was stirred for 30 min at room temperature, then at 60° C. for 24 h and poured into ice water (4 L). The aqueous solution was acidified to pH about 2 with conc. HCl and the unreacted starting material extracted with EtOAc/THF=3/1 mixture. Upon adjusting the pH of the water layer to about 9, the product was extracted with 1:1 EtOAc:THF mixture (10×500 mL). The combined extracts were washed with brine, dried over Na2SO4 and solvent evaporated out to afford 22 g (68%) of crude carbazole (84), reasonable pure by LC/MS. It was used in the next step without further purification.

Provenance & Evidence