[CH:1](=O)[C:2]1[C:3]([O:8][CH3:9])=[CH:4][CH:5]=[CH:6][CH:7]=1.C(S)CCS.B(F)(F)F.S1CCCCS1.[Li]CCCC.[C:31](OC)(=[O:40])[CH:32]=[CH:33][C:34]1[CH:39]=[CH:38][CH:37]=[CH:36][CH:35]=1.CN1CCN(C)C1=O>C(Cl)Cl>[CH3:9][O:8][C:3]1[CH:4]=[CH:5][CH:6]=[C:7]2[C:2]=1[CH2:1][CH:33]([C:34]1[CH:39]=[CH:38][CH:37]=[CH:36][CH:35]=1)[CH2:32][C:31]2=[O:40]o-Anisaldehyde (20.5 g) was treated with 1,3-propanedithiol (24 ml) in the presence of BF3 etherate (4 ml) and CH2Cl2 (300 ml). This dithiane derivative (4.7 g) was reacted with n-BuLi (2.5 M hexane solution) (7.3 ml), methyl cinnamate (3.4 g) and 1,3-dimethyl-2-imidazolidone (4.6 ml) affording the desired product (M+H)+ 389. Desulfurization was accomplished with Raney Nickel and EtOH, followed by hydrolysis to the desired carboxylic acid. Cyclization to the desired 5-methoxy-3-phenyl-1-tetralone was accomplished by heating with polyphosphoric acid, (M+H)+ 253.
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