Ammonia → 1,2,3,3a,4,8b-Hexahydrocyclopenta[b]indole

HRID 2278660Notes

Reaction equation

C([BH3-])#N.[Na+].[CH2:5]1[C:16]2[C:15]3[CH:14]=[CH:13][CH:12]=[CH:11][C:10]=3[NH:9][C:8]=2[CH2:7][CH2:6]1.N>C(O)(=O)C.O>[CH2:5]1[CH:16]2[CH:8]([NH:9][C:10]3[CH:11]=[CH:12][CH:13]=[CH:14][C:15]=32)[CH2:7][CH2:6]1

Participants

Conditions

Temperature: 15 °C

Procedure

1.9 g of sodium cyanoborohydride are added in portions to a solution of 1.5 g of 1,2,3,4-tetrahydrocyclopenta[b]indole in 40 ml of acetic acid cooled to 15° C. The reaction medium is stirred for 20 hours while allowing it to rise to ambient temperature and then the pH is brought to neutrality with a 28% aqueous ammonia solution. The reaction mixture is diluted with water and then extracted with dichloromethane, and the organic phase is washed with a saturated sodium chloride solution, dried over magnesium sulfate, filtered, and concentrated under reduced pressure. The residue is purified by silica column chromatography, elution being carried out with a mixture of heptane and ethyl acetate (95/05), so as to give 1.3 g of 1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole in the form of a colorless oil.

Workup

customto rise to ambient temperature
extractionextracted with dichloromethane
washthe organic phase is washed with a saturated sodium chloride solution
dry with materialdried over magnesium sulfate
filtrationfiltered
concentrationconcentrated under reduced pressure
customThe residue is purified by silica column chromatography, elution
additionbeing carried out with a mixture of heptane and ethyl acetate (95/05)

Sources & evidence

ORD record: ord-c258dd252fbc4eb68f062071fe217b09
Source dataset: uspto-grants-2015_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09133168B2

Reaction notes

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