Methyl p-toluenesulfonate → N-Methyl 3,4-dihydroisoquinolinium p-toluene sulfonate

Participants

Reaction Conditions

Reaction Steps

The title compound was prepared using the procedure described by Koelsch et al in J. Am. Chem. Soc. (1953) 75, 2095. In a 250-ml one-necked round-bottomed flask equipped with a magnetic stir bar and a reflux condenser were placed 3,4-dihydroisoquinoline (8.27 grams, 63 mmol) and 40 ml of methanol. The mixture was stirred and cooled to 0° C. A solution of methyl p-toluenesulfonate (11.73 g, 63 mmol) and 70 ml of methanol was added dropwise. The color of the solution remained clear and yellow. The mixture was heated to reflux for 6 hours. The methanol was then removed in vacuo to provide a quantitative yield (20 g) of an off-white solid (mp 115°-119° C.). The solid was pulverized and washed with 40 ml of acetone at room temperature. Suction filtration provided a white solid in 88% yield: mp 124°-127° C.

Provenance & Evidence