p-Toluenesulfonic acid → Methyl 10-methoxy-5H-dibenz[b,f]azepine-5-carboxylate

Participants

Reaction Conditions

Reaction Steps

Crude 10-Oxo-10,11-dihydro-dibenzo[b,f]azepine-5-carboxylic acid methyl ester (22.3 g, 0.083 mol, 1 eq.) is dissolved in methanol (112 mL) at 50° C. A catalytic amount of p-toluenesulfonic acid (0.445 mg) is added, followed by trimethyl orthoformate (11.5 mL, 1.25 eq.). The mixture is allowed to react for 5 hours before methanol is allowed to distill off. Fresh methanol is added continuously to replace the distillate. When 100 mL of methanol have been distilled, the mixture is allowed to cool down to 25° C. in 1 hour. The suspension is further cooled down to 3° C. in 20 minutes, stirred at this temperature for 1 hour and filtered. The solid is washed with cold methanol and dried in vacuum for 15 hours (50° C., 50 mbar). Pure title compound is obtained as a light yellow powder (18.02 g, 80.8% yield).

Provenance & Evidence