Hydrochloric Acid → trans-2-benzyl-2,3,4,4a,5,9b-hexahydro-5-phenyl-1H-pyrido-[4,3-b]indole Hydrochloride

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Reaction Steps

To a solution of 0.140 moles of borane in 150 ml. of tetrahydrofuran stirred at 0° C. in a three-necked round bottom flask fitted with magnetic stirrer, thermometer, condenser and addition funnel, and maintained under a nitrogen atmosphere, was added a solution of 23.9 g. (0.071 mole) of 2-benzyl-5-phenyl-1,2,3,4-tetrahydropyrido[4,3-b]indole in 460 ml. of dry tetrahydrofuran. The addition was carried out at such a rate as to maintain the reaction temperature below 9° C. When the addition was completed the resulting mixture was heated to reflux and maintained at this temperature for one hour. The solvent was then evaporated in vacuo to afford a white solid mass which was suspended in 40 ml. of dry tetrahydrofuran and heated, slowly at first, with 180 ml. of a 1:1 by volume mixture of acetic acid and 5 N hydrochloric acid. The resulting suspension was heated at reflux for one hour, then cooled. Evaporation of tetrahydrofuran and part of the acetic acid resulted in precipitation of a white solid which was separated by filtration and washed with water. The solid was resuspended in tetrahydrofuran, filtered, washed with ethyl ether and air dried to afford 16.7 g. (63%) of the desired trans-isomer. M.P. 256°-260° C.

Provenance & Evidence