Benzene → trans-5-phenyl-2,3,4,4a,5,9b-hexahydro-1H-pyrido[4,3-b]indole

Participants

Reaction Steps

A solution of ethyl chloroformate (22 g., 0.2 mole) in 100 ml. dry benzene was added to a solution of (±)-trans-2-cyclopropylmethyl-2,3,4,4a,5,9b-hexahydro-5-phenyl-1H-pyrido[4,3-b]indole (16 g. crude material, prepared as described above, 0.047 moles in theory) in 400 ml. anhydrous benzene with stirring. The resulting mixture was refluxed for three hours. As the mixture was refluxing, a whitish solid precipitated. After refluxing, the mixture was cooled and filtered to remove the precipitate, then the filtrate was evaporated to dryness under vacuum, yielding a yellow oil. This oil was dissolved in 400 ml. n-butanol, 40 g. of KOH pellets were added, and the resulting mixture was refluxed with stirring for one hour. After refluxing, the mixture was cooled, and concentrated under vacuum. Water and toluene were added and the mixture was placed in a separatory funnel. The toluene layer was removed and washed with water until the waste water was neutral to litmus. The toluene layer was then extracted four times with 125 ml. of 1 molar tartaric acid. The combined extracts were then washed once with ether, made basic by addition of 50% aqueous NaOH, cooled, and extracted two times with 75 ml. CHCl3. The CHCl3 extract was washed with water until the wash water was neutral to litmus, dried with K2CO3, filtered, and evaporated to dryness under vacuum, yielding 9.7 g. of an oil. This was left in a refrigerator overnight, then was triturated with hexane, yielding a solid. Recrystallization from hexane yielded 4.9 g. of the title compound, m.p. 94°-94.7° C.

Provenance & Evidence