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

HRID 2379008Notes

Reaction equation

[CH:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][CH2:3][N:2]=1.[C:11]1([CH3:22])[CH:16]=[CH:15][C:14]([S:17]([O:20]C)(=[O:19])=[O:18])=[CH:13][CH:12]=1>CO>[C:11]1([CH3:22])[CH:12]=[CH:13][C:14]([S:17]([O-:20])(=[O:18])=[O:19])=[CH:15][CH:16]=1.[CH3:11][N+:2]1[CH2:3][CH2:4][C:5]2[C:10](=[CH:9][CH:8]=[CH:7][CH:6]=2)[CH:1]=1

Participants

Conditions

Temperature: 0 °C

Procedure

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 (11.73g, 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 (top 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. 1H NMR (D2O): δ2.27 (s,3H), 3.15 (t,2H), 3.73 (S,3H), 3.93 (t,2H), 7.18-7.78 (m,8H), 8.77 (s,1H). Impurities observed at 4.46 (s), 8.0-8.3 (m), 9.4 (s) were due to N-methyl-isoquinolinium p-toluenesulfonate.

Workup

customIn a 250-mL one-necked round-bottomed flask equipped with a magnetic stir bar and a reflux condenser
temperatureThe mixture was heated
temperatureto reflux for 6 hours
customThe methanol was then removed in vacuo

Sources & evidence

ORD record: ord-de108e4c75c04e1191719fb61b7905d7
Source dataset: uspto-grants-1994_11
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US05360569

Reaction notes

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