Boron trifluoride etherate → Ethyl-1-propyl-1,3,4,9-tetrahydro-6-(phenylmethoxy)pyrano[3,4-b]indole-1-acetate

HRID 37701

Reaction equation

HRID 37701 reaction equation
[CH:1]1[CH:6]=[CH:5][C:4]([CH2:7][O:8][C:9]2[CH:14]=[CH:13][C:12]3[NH:15][CH:16]=[C:17]([CH2:18][CH2:19][OH:20])[C:11]=3[CH:10]=2)=[CH:3][CH:2]=1.[C:21]([CH2:26][C:27]([O:29][CH2:30][CH3:31])=[O:28])(=O)[CH2:22][CH2:23][CH3:24].B(F)(F)F.CCOCC>C(Cl)Cl>[CH2:30]([O:29][C:27](=[O:28])[CH2:26][C:21]1([CH2:22][CH2:23][CH3:24])[C:16]2[NH:15][C:12]3[C:11]([C:17]=2[CH2:18][CH2:19][O:20]1)=[CH:10][C:9]([O:8][CH2:7][C:4]1[CH:3]=[CH:2][CH:1]=[CH:6][CH:5]=1)=[CH:14][CH:13]=3)[CH3:31]

Participants

5

Reactant 3

HCID 8000Boron trifluoride etherateHCID 238498Ethyl 3-oxohexanoateHCID 7448495-Benzyloxy-3-(2-hydroxyethyl)indole

Product 1

HCID 19935728Ethyl-1-propyl-1,3,4,9-tetrahydro-6-(phenylmethoxy)pyrano[3,4-b]indole-1-acetateYield 79.4%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

A solution of 5-benzyloxytryptophol (4.72 g, 17 mmol) and ethyl butyrylacetate (3.16 g, 20 mmol) in methylene chloride (75 ml) is treated dropwise with boron trifluoride etherate (3 mL) and stirred under nitrogen at room temperature overnight. The reaction mixture is diluted with methylene chloride (250 mL) and sequentially washed with 5% aqueous sodium bicarbonate (2×100 mL) and water (2×50 mL). The organic phase is dried (MgSO4), filtered, and evaporated to afford 7.0 g of a crude dark oil. Purification by flash column chromatography (ethyl acetate:hexane, 1:9 eluent) on silica gel (50:1 ratio, 230-400 mesh) affords the title compound (5.5 g, 79%) as a slightly amber oil homogeneous by TLC.

Workup

  1. washsequentially washed with 5% aqueous sodium bicarbonate (2×100 mL) and water (2×50 mL)
  2. dry with materialThe organic phase is dried (MgSO4)
  3. filtrationfiltered
  4. customevaporated
  5. customto afford 7.0 g of a crude dark oil
  6. customPurification by flash column chromatography (ethyl acetate:hexane, 1:9 eluent) on silica gel (50:1 ratio, 230-400 mesh)

Sources & evidence

ORD record
ord-c478eada40d1417c9e940940bd675cfc
Source dataset
uspto-grants-1995_05
Patent number
US05420289

Linked notes

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