Reaction #56188

Reaction equation

tetrahydrofuran

hydrochloric acid

borane

tetrahydrofuran

tetrahydrofuran

2-benzyl-5-phenyl-1,2,3,4-tetrahydropyrido[4,3-b]indole

→

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

Solvents

acetic acid

Conditions

Workup

1. 1
   Otherfitted with magnetic stirrer
2. 2
   workup.ADDITIONthermometer, condenser and addition funnel
3. 3
   Temperaturemaintained under a nitrogen atmosphere
4. 4
   workup.ADDITIONwas added a solution of 23.9 g
5. 5
   workup.ADDITIONThe addition
6. 6
   Temperatureto maintain the reaction temperature below 9° C
7. 7
   workup.ADDITIONWhen the addition
8. 8
   Temperaturewas heated
9. 9
   Temperatureto reflux
10. 10
    Temperaturemaintained at this temperature for one hour
11. 11
    OtherThe solvent was then evaporated in vacuo
12. 12
    Otherto afford a white solid mass which
13. 13
    TemperatureThe resulting suspension was heated
14. 14
    Temperatureat reflux for one hour
15. 15
    Temperaturecooled
16. 16
    OtherEvaporation of tetrahydrofuran and part of the acetic acid
17. 17
    Otherresulted in precipitation of a white solid which
18. 18
    Otherwas separated by filtration
19. 19
    Washwashed with water
20. 20
    Filtrationfiltered
21. 21
    Washwashed with ethyl ether and air
22. 22
    Otherdried
23. 23
    Otherto afford 16.7 g

Procedure

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.

Source