Acetate → 6-Hydroxy-2-methyl-2,3-dihydro-1h-inden-1-one

Reaction equation

[Br-].[Al+3].[Br-].[Br-].CO[CH:7]1[CH2:15][C:14]2[C:9](=CC=[CH:12][CH:13]=2)[C:8]1=[O:16].[C:17]([O-:20])(=O)[CH3:18].Cl.[CH:22]1C=CC=CC=1>>[OH:20][C:17]1[CH:18]=[C:9]2[C:14]([CH2:15][CH:7]([CH3:22])[C:8]2=[O:16])=[CH:13][CH:12]=1

Participants

Reactant 5

HCID 175Acetate

HCID 241Benzene2×

HCID 313Hydrochloric Acid

HCID 166749Bromhydrol

HCID 10866644Methoxy indanone

Product 1

HCID 2343386-Hydroxy-2-methyl-2,3-dihydro-1h-inden-1-one

Procedure

To a stirred solution of anhydrous aluminum bromide (69.82 g, 0.261 mole) in anhydrous benzene (250 mL) kept under nitrogen is added dropwise over 30 minutes a solution of the methoxy indanone (18 g, 0.102 mole) of Step C, in benzene (60 mL). The mixture is gently refluxed for 3 hours (TLC, dichloromethaneethyl acetate 8:2, UV), cooled in an ice bath and treated dropwise with 6N-HCl (ca. 200 mL) to decompose the aluminum complex. The aqueous phase is extracted with ether (3 times), the extracts are concentrated at reduced pressure and extracted with 2.5N-NaOH (2×75 mL and 1×50 mL). The basic extracts are neutralized (ice bath) with concentrated HCl and the oil that separates is extracted with ether (3 times). The combined extracts are washed with brine, dried (MgSO4) and evaporated to yield an oil that readily solidifies. The crude material is flash chromatographed (on silica Merck-60, gradient CH2Cl2, CH2Cl2 -ethyl acetate 85:15 ) to provide the pure title compound (13.60 g, nearly colorless solid, 82%).