Acetone → 2,3,6,7,8,9-Hexahydro-2,2,6,6,9,9-hexamethyl-4H-naphtho[2,3-b]pyran-4-one

HRID 964511Notes

Reaction equation

HRID 964511 reaction equation
O[CH2:2][C:3]([C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1)=[O:4].N1CCC[CH2:12]1.[CH3:16][C:17]([CH3:19])=[O:18].[CH3:20][C:21]1[CH:22]=[CH:23][C:24](S(O)(=O)=O)=[CH:25][CH:26]=1>C1C=CC=CC=1.Cl>[CH3:16][C:17]1([CH3:19])[CH2:2][C:3](=[O:4])[C:5]2[C:6](=[CH:7][C:8]3[C:24]([CH3:25])([CH3:12])[CH2:23][CH2:22][C:21]([CH3:20])([CH3:26])[C:9]=3[CH:10]=2)[O:18]1

Participants

7

Reactant 4

HCID 180AcetoneHCID 6101p-Toluenesulfonic acidHCID 31268PyrrolidineHCID 68490alpha-Hydroxyacetophenone

Product 1

HCID 703426452,3,6,7,8,9-Hexahydro-2,2,6,6,9,9-hexamethyl-4H-naphtho[2,3-b]pyran-4-oneYield 26%

Reagents, catalysts & solvents 2

HCID 241BenzeneSolventHCID 313Hydrochloric AcidSolvent

Conditions

Temperature
25 °C

Procedure

A solution of the above hydroxyacetophenone (1.86 g, 7.5 mmol), pyrrolidine (590 mg, 7.5 mmol), acetone (850 mg, 14.6 mmol), and a catalytic amount of p-TsOH in benzene (650 ml) was heated at reflux for 48 hours. The mixture was cooled to 25° C. and diluted with 1N HCl (35 ml). Aqueous work up (Et2O extraction) gave a yellowish brown solid. Recrystallization from hexane afforded 2,3,6,7,8,9-hexahydro-2,2,6,6,9,9-hexamethylbenzo [g]chromen-4-one (structure 1) as fine white crystals (560 mg, 1.95 mmol, 26%): 1H NMR (400 MHz, CDCl3) δ 7.3 (s, 1H), 6.85 (s, 1H), 2.68 (s, 2H), 1.68 (s, 4H), 1.45 (s, 6H), 1.26 (s, 12H).

Workup

  1. temperatureat reflux for 48 hours
  2. extractionAqueous work up (Et2O extraction)
  3. customgave a yellowish brown solid
  4. customRecrystallization from hexane

Sources & evidence

ORD record
ord-a6852d31c8e1402d989d19000c256326
Source dataset
uspto-grants-1998_06
Patent number
US05770383

Reaction notes

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