Dimethyl Sulfate → N-Formyl-2-methoxy-N-methyl-alpha-(3-methyl-2-thienyl)benzeneethanamine

Participants

Reaction Steps

To an ice-water chilled solution of 5.10 g of N-formyl-2-hydroxy-N-methyl-α-(3-methyl-2-thienyl)benzeneethanamine and 100 ml of tetrahydrofuran, was added 2.24 g of potassium t-butoxide and then a solution of 2.52 g of dimethylsulfate and 25 ml of tetrahydrofuran dropwise, with stirring. The mixture was stirred at ice-bath temperature for 30 min, at room temperature for one hr, and at reflux for 30 mins. Additional dimethylsulfate and potassium t-butoxide were added and the mixture was refluxed for 20 min. The reaction mixture was decanted into 40 ml of water and basified with 10% sodium hydroxide solution. The mixture was extracted with dichloromethane. The combined organic phase was dried over anhydrous sodium sulfate, filtered and concentrated. The residue was combined with a previous sample. The combined residue was purified by preparative HPLC (Water Associates Prep LC/System 500, silica gel, material applied as a solution in dichloromethane, eluted with ethyl acetate-hexane (1:1, 200 ml/min flow rate). The appropriate fractions were combined and concentrated. The residue crystallized during refrigerated storage. Recrystallization from cyclohexane afforded 3.5 g of the product, mp 80°-83° C.

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