p-Toluenesulfonic acid → 1-Methyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid ethyl ester

HRID 1834384Notes

Reaction equation

HRID 1834384 reaction equation
[C:1]([O:7][CH2:8][CH3:9])(=[O:6])[CH2:2][C:3]([CH3:5])=O.[CH:10]1[CH:11]=[CH:12][C:13]2[NH:18][CH:17]=[C:16]([CH2:19][CH2:20][OH:21])[C:14]=2[CH:15]=1.C1(C)C=CC(S(O)(=O)=O)=CC=1>C1C=CC=CC=1>[CH2:8]([O:7][C:1](=[O:6])[CH2:2][C:3]1([CH3:5])[C:17]2[NH:18][C:13]3[C:14]([C:16]=2[CH2:19][CH2:20][O:21]1)=[CH:15][CH:10]=[CH:11][CH:12]=3)[CH3:9]

Participants

5

Reactant 3

HCID 6101p-Toluenesulfonic acid2×HCID 8868Ethyl AcetoacetateHCID 10685Tryptophol

Product 1

HCID 537142471-Methyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid ethyl ester

Reagents, catalysts & solvents 1

HCID 241BenzeneSolvent

Procedure

Ethyl acetoacetate (23.4 g., 0.18 moles) is added to a solution of the starting material of formula II, tryptophol (10.0 g., 0.06 moles). in 200 ml. of benzene. After standing for 10 minutes, p-toluenesulfonic acid (1.3 g.) and about 5 g. of hydrated alkali-aluminum silicate (Molecular Sieves No. 4) are added. The mixture is subjected to reflux for thirty minutes, 600 mg. more of p-toluenesulfonic acid is added and refluxing continued for 21/2 hours. The molecular sieves are collected and the benzene solution washed successively with 5% sodium bicarbonate and water, dried over sodium sulfate, and evaporated under reduced pressure to dryness affording an oil. The oil is subjected to chromatography on silica gel. Elution with 5% ether in benzene yields the ester, 1-methyl-1,3,4,9-tetrahydropyrano[3,4-b]indole-1-acetic acid ethyl ester, as an oil, γ max/CHCl3 1715 cm-1.

Workup

  1. temperatureto reflux for thirty minutes
  2. temperaturerefluxing
  3. custom2 hours
  4. customThe molecular sieves are collected
  5. washthe benzene solution washed successively with 5% sodium bicarbonate and water
  6. dry with materialdried over sodium sulfate
  7. customevaporated under reduced pressure to dryness
  8. customaffording an oil
  9. washElution with 5% ether in benzene

Sources & evidence

ORD record
ord-e2bb159171d74a6a8cf06b20383590bc
Source dataset
uspto-grants-1978_01
Patent number
US04070371

Reaction notes

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