1-Methoxy-3-trimethylsilyloxy-1,3-butadiene → 3,4,5,6-Tetrahydrobenzo[c]quinolizin-3-(4aH)-one

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Reaction Steps

To a stirred solution of compound 4 [(QW)n=H, R3=R4=H] (4 g, 14.42 mmol) of the example 3, in 75 ml of anhydrous CH2Cl2 under argon at −10° C. is added, dropwise in 7 min, 28.84 ml of a 1M solution of TiCl4 in CH2Cl2 maintaining the temperature below −5° C. Then 1-methoxy-3-(trimethylsilyloxy)-1-3-butadiene (compound 6, R1=MeO, R2=H, R6=H) (3.29 ml, 17.3 mmol) is added by syringe at 0° C., and the reaction was left aside at room temperature for 1 h. The reaction mixture is added, cautiously, with 100 ml of NaHCO3 satured solution, and then stirred for 30 min. The organic layer is separated, washed with water, filtered on Celite and dried over Na2SO4. After removal of the solvent the crude product is purified by flash column chromatography (eluant light-petroleum ether/ethyl acetate 1:4) affording 0.72 g (25% yield) of the expected product (white crystals, m.p.: 135-137° C.).

Provenance & Evidence