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

HRID 1833692Notes

Reaction equation

HRID 1833692 reaction equation
[C:1]([O:7][CH2:8][CH3:9])(=[O:6])[CH2:2][C:3]([CH3:5])=[O:4].[NH:10]1[C:18]2[C:13](=[CH:14][CH:15]=[CH:16][CH:17]=2)[C:12]([CH2:19][CH2:20]S)=[CH:11]1.C1C=CC2NC=C(CCO)C=2C=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:11]2[NH:10][C:18]3[C:13]([C:12]=2[CH2:19][CH2:20][O:4]1)=[CH:14][CH:15]=[CH:16][CH:17]=3)[CH3:9]

Participants

6

Reactant 4

HCID 6101p-Toluenesulfonic acid2×HCID 8868Ethyl AcetoacetateHCID 10685TryptopholHCID 122442792-(1H-indol-3-yl)ethane-1-thiol

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, νmaxCHCl3 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-aa1068c5b149479285f13f93c12c7271
Source dataset
uspto-grants-1978_01
Patent number
US04066780

Reaction notes

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