Ammonium Chloride → (3R,4R)-7-methoxy-3-(4-methoxyphenyl)-3-methyl-4-(2-propenyl)thiochroman

Participants

Reaction Steps

A solution of the (3S)-7-methoxy-3-(4-methoxyphenyl)-3-methylthiochroman-4-one prepared in Example 1 (15 g, 0.048 mol) in anhydrous tetrahydrofuran (250 ml) was cooled to −78° C. To this solution, lithium aluminum hydride (905 mg, 0.024 mol) was added dropwise and the resulting mixture was stirred for 12 hours at room temperature. After the reaction was completed, saturated aqueous ammonium chloride was added to the reaction mixture, which was then extracted three times with ethyl acetate. The combined organic layers were washed with water and saturated aqueous sodium chloride, and then dried over anhydrous magnesium sulfate. After distilling off the solvent, zinc iodide (18.0 g, 0.053 mol) and allyltrimethylsilane (15 ml, 0.088 mol) were added dropwise to a solution of the residue in 1,2-dichloroethane (300 ml) while cooling at 0° C., followed by stirring overnight at room temperature. After the reaction was completed, water was added to the reaction mixture, which was then extracted three times with dichloromethane. The combined organic layers were washed with water and saturated aqueous sodium chloride, and then dried over anhydrous magnesium sulfate. After distilling off the solvent, the residue was purified by silica gel column chromatography (eluent: ethyl acetate/hexane=1/4) to give (3R,4R)-7-methoxy-3-(4-methoxyphenyl)-3-methyl-4-(2-propenyl)thiochroman (10.8 g, Yield 67%).

Provenance & Evidence