Sulfuric Acid → 2-methyl-2,3,5,6,7,8-hexahydro-1H-cyclopenta[b]naphthalen-1-one

HRID 2061530Notes

Reaction equation

HRID 2061530 reaction equation
[CH:1]1[C:10]2[CH2:9][CH2:8][CH2:7][CH2:6][C:5]=2[CH:4]=[CH:3][C:2]=1[C:11](=[O:14])[CH2:12][CH3:13].[CH2:15]1N2CN3CN(C2)CN1C3.C(OC(=O)C)(=O)C.[OH-].[Na+].S(=O)(=O)(O)O.C1CC(=O)C=C2C=1C=CC=C2>O.C(OCC)(=O)C>[CH3:13][CH:12]1[C:11](=[O:14])[C:2]2=[CH:1][C:10]3[CH2:9][CH2:8][CH2:7][CH2:6][C:5]=3[CH:4]=[C:3]2[CH2:15]1

Participants

9

Reactant 6

HCID 1118Sulfuric AcidHCID 4101HexamethylenetetramineHCID 7918Acetic AnhydrideHCID 14798Sodium HydroxideHCID 40859601-(5,6,7,8-Tetrahydronaphthalen-2-yl)propan-1-oneHCID 20192716Naphthalen-3-one

Product 1

HCID 224992222-methyl-2,3,5,6,7,8-hexahydro-1H-cyclopenta[b]naphthalen-1-one

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 8857Ethyl AcetateSolvent

Conditions

Temperature
80 °C

Procedure

According to the procedure of Bhattacharya et. al (Synth. Commun 1996., 26, 1775-1784.) a mixture of 1-(5,6,7,8-tetrahydro-naphthalen-2-yl)-propan-1-one (37.6 g), hexamethylenetetramine (44.9 g) and acetic anhydride (38.8 mL) is heated with stirring at 80° C. for 23 hours. The mixture is allowed to cool, and added slowly to a stirred mixture of ethyl acetate (200 mL) and aqueous sodium hydroxide (200 mL, 2M). The organic layer is separated, washed with aqueous HCl, brine, and dried (Na2SO4). The solvent is removed to give a brown oil. This is added cautiously to concentrated sulfuric acid (120 mL) and the resulting mixture is heated at 55° C. for 5 hours followed by room temperature for 18 hours. The reaction is diluted with water and extracted with dichloromethane. After drying (Na2SO4) the solvent is removed to give an oil. The product is purified by chromatography (silica, ethyl acetate/hexane) to give a geometrical mixture of isomers containing 2-Methyl-1,2,6,7,8,9-hexahydro-cyclopenta[.a.]naphthalen-3-one and the title compound.

Workup

  1. temperatureis heated
  2. temperatureto cool
  3. customThe organic layer is separated
  4. washwashed with aqueous HCl, brine
  5. dry with materialdried (Na2SO4)
  6. customThe solvent is removed
  7. customto give a brown oil
  8. temperaturethe resulting mixture is heated at 55° C. for 5 hours
  9. waitfollowed by room temperature for 18 hours
  10. extractionextracted with dichloromethane
  11. dry with materialAfter drying (Na2SO4) the solvent
  12. customis removed
  13. customto give an oil
  14. customThe product is purified by chromatography (silica, ethyl acetate/hexane)
  15. customto give
  16. additiona geometrical mixture of isomers
  17. additioncontaining 2-Methyl-1,2,6,7,8,9-hexahydro-cyclopenta[.a

Sources & evidence

ORD record
ord-c80cc92d0e7646ec927d99d618989781
Source dataset
uspto-grants-2012_10
Patent number
US08283362B2

Reaction notes

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