1,2,3,3a,8,8a-Hexahydro-alpha-oxo-1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, ethyl ester → 1,2,3,3a,8,8a-Hexahydro-alpha-oxo-1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, n-hexyl ester

HRID 258150Notes

Reaction equation

HRID 258150 reaction equation
[O:1]=[C:2]([C:8]1[CH:9]=[C:10]2[C:14](=[CH:15][CH:16]=1)[N:13]([CH3:17])[CH:12]1[N:18]([CH3:21])[CH2:19][CH2:20][C:11]21[CH3:22])[C:3]([O:5][CH2:6][CH3:7])=[O:4]>C(O)CCCCC.[Ti]>[O:1]=[C:2]([C:8]1[CH:9]=[C:10]2[C:14](=[CH:15][CH:16]=1)[N:13]([CH3:17])[CH:12]1[N:18]([CH3:21])[CH2:19][CH2:20][C:11]21[CH3:22])[C:3]([O:5][CH2:6][CH2:7][CH2:3][CH2:2][CH2:8][CH3:16])=[O:4]

Participants

4

Reactant 1

HCID 867464181,2,3,3a,8,8a-Hexahydro-alpha-oxo-1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, ethyl ester

Product 1

HCID 867464251,2,3,3a,8,8a-Hexahydro-alpha-oxo-1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, n-hexyl esterYield 164.8%

Reagents, catalysts & solvents 2

HCID 23963TitaniumCatalystHCID 81031-HexanolSolvent

Procedure

To a stirred solution of 1,2,3,3a,8,8a-hexahydro-α-oxo-1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, ethyl ester (3.0 g) in n-hexyl alcohol (73.6 ml) was added at 0° C. under a nitrogen atmosphere, titanium IV ethoxide (0.83 ml). The mixture was warmed to room temperature and heated for 2 hours keeping the temperature between 60°-80° C. The excess n-hexyl alcohol was removed by distillation under high vacuum. The residue was taken up in ethyl acetate, washed twice with 100 ml portions of saturated aqueous NH4Cl solution, twice with 100 ml portions of saturated aqueous NaHCO3 solution and once with 100 ml of brine. The organic phase was dried (NaSO4), filtered, and concentrated to afford an oil which was purified using preparative HPLC (silica gel, 3% methanol in dichloromethane as the loading solvent and eluent). The appropriate fractions were combined and the solvents removed under reduced pressure yielding 2.93 g of 1,2,3,3a,8,8a-hexahydro-α-oxo-1,3a,8 -trimethyl-5-pyrrolo[2,3-b]indole acetic acid, n-hexyl ester, as an oil.

Workup

  1. temperatureheated for 2 hours
  2. custombetween 60°-80° C
  3. customThe excess n-hexyl alcohol was removed by distillation under high vacuum
  4. washwashed twice with 100 ml portions of saturated aqueous NH4Cl solution, twice with 100 ml portions of saturated aqueous NaHCO3 solution and once with 100 ml of brine
  5. dry with materialThe organic phase was dried (NaSO4)
  6. filtrationfiltered
  7. concentrationconcentrated
  8. customto afford an oil which
  9. customwas purified
  10. customthe solvents removed under reduced pressure

Sources & evidence

ORD record
ord-685aca4118134687af1827aa9ba4adcd
Source dataset
uspto-grants-1993_11
Patent number
US05264587

Reaction notes

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