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

HRID 269445Notes

Reaction equation

HRID 269445 reaction equation
Br[C:2]([CH3:7])([CH3:6])[C:3](Br)=[O:4].[Al+3].[Cl-].[Cl-].[Cl-].[CH2:12]1[C:21]2[C:16](=[CH:17][CH:18]=[CH:19][CH:20]=2)[CH2:15][CH2:14][CH2:13]1>C(Cl)Cl>[CH3:6][CH:2]1[C:3](=[O:4])[C:18]2=[CH:17][C:16]3[CH2:15][CH2:14][CH2:13][CH2:12][C:21]=3[CH:20]=[C:19]2[CH2:7]1

Participants

5

Reactant 3

HCID 8404TetralinHCID 886852-Bromo-2-methylpropionyl bromideHCID 6451240Aluminum(III) Chloride

Product 1

HCID 224992222-methyl-2,3,5,6,7,8-hexahydro-1H-cyclopenta[b]naphthalen-1-oneYield 31.1%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Conditions

Temperature
0 °C

Procedure

A total of 145 g (0.63 mol) of 2-bromo-2-methylpropanoyl bromide were added dropwise to a suspension of 223 g (1.67 mol) AlCl3 in 200 ml of CH2Cl2 with vigorous stirring for 15 min at 0° C. This mixture was stirred for 45 min at this temperature; then a solution of 83.4 g (0.63 mol) of tetraline in 200 ml of CH2Cl2 was added dropwise. The mixture was slowly warmed to ambient temperature, stirred additionally overnight, and, then, poured on 1000 cm3 of ice. The organic layer was separated, the aqueous layer was extracted with 3×300 ml of CH2Cl2. The combined organic fractions were dried over MgSO4 and evaporated to dryness. Fractional distillation gave a yellowish mixture of the title indanones, b.p. 183-190° C./7 mm Hg. This mixture was recrystallized from 300 ml of n-hexane. Crystals of 2-methyl-1,2,6,7,8,9-hexahydro-3H-cyclopenta[a]naphthalen-3-one that precipitated at −30° C. were filtered off, washed with 2×25 ml of cold n-hexane, and dried in vacuum. Yield 56.5 g (45%). The filtrate was evaporated to dryness and dried in vacuum. This procedure gave 39.3 g (31%) of pure 2-methyl-2,3,5,6,7,8-hexahydro-1H-cyclopenta[b]naphthalen-1-one.

Workup

  1. stirringThis mixture was stirred for 45 min at this temperature
  2. temperatureThe mixture was slowly warmed to ambient temperature
  3. stirringstirred additionally overnight
  4. customThe organic layer was separated
  5. extractionthe aqueous layer was extracted with 3×300 ml of CH2Cl2
  6. dry with materialThe combined organic fractions were dried over MgSO4
  7. customevaporated to dryness
  8. distillationFractional distillation
  9. customgave
  10. customThis mixture was recrystallized from 300 ml of n-hexane
  11. customCrystals of 2-methyl-1,2,6,7,8,9-hexahydro-3H-cyclopenta[a]naphthalen-3-one that precipitated at −30° C.
  12. filtrationwere filtered off
  13. washwashed with 2×25 ml of cold n-hexane
  14. customdried in vacuum
  15. customThe filtrate was evaporated to dryness
  16. customdried in vacuum

Sources & evidence

ORD record
ord-cde6c4c257c149bbad5b45dc48a885e0
Source dataset
uspto-grants-2008_11
Patent number
US07446216B2

Reaction notes

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