Acetyl chloride → 5,8-Dimethoxy-2-acetyl-3,4-dihydronaphthalene
Reaction equation
[CH3:1][O:2][C:3]1[CH:12]=[CH:11][C:10]([O:13][CH3:14])=[C:9]2[C:4]=1[CH2:5][CH2:6][CH:7]=[CH:8]2.[C:15](Cl)(=[O:17])[CH3:16].[Cl-].[Cl-].[Cl-].[Al+3]>>[C:15]([C:6]1[CH2:7][CH2:8][C:9]2[C:4](=[C:3]([O:2][CH3:1])[CH:12]=[CH:11][C:10]=2[O:13][CH3:14])[CH:5]=1)(=[O:17])[CH3:16]Participants
4
Procedure
In spite of the fact that in literature the attempts of acylating the compound II were reported as fruitless or non interesting because of the low yields, the 5,8-dimethoxy-3,4-dihydronaphthalene II is treated with acetyl chloride in the presence of an excess of aluminium trichloride, preferably 5-9 moles of aluminium trichloride for one mole of acyl chloride, at the temperature of −35°+25° C., preferably at 0° C. After the usual work-up and crystallisation with ethyl acetate, the product, 2-acetyl-5,8-dimethoxy-3,4-dihydronaphthalene is obtained in yields higher than 70%.