Thionyl Chloride → cis-2-Methoxycarbonyl-3-methyltetrahydroquinoline

Participants

Reaction Steps

To a solution of cis-2-methoxycarbonyl-3-methyltetrahydroquinoline (8.36 g, 40.7 mmol)in methanol (65 mL) was added sodium methoxide (14.8 mmol) in methanol (20 mL) at room temperature. The mixture was refluxed for 3 h and allowed to cool to room temperature. Thionyl chloride (7.23 mL, 99.2 mmol) was added and the resulting mixture was refluxed for 3 h. After the solvent was evaporated, the residue was dissolved in water and adjusted to pH 8 by using saturated aqueous sodium bicarbonate. The mixture was extracted with ethyl acetate. The organic layer was washed with: water and brine, dried over magnesium sulfate, and concentrated. The residue was purified by column chromatography with 15:1 hexane/ethyl acetate to give 3.94 g of cis-2-methoxycarbonyl-3-methyltetrahydroquinoline (47%) and 3.17 g of trans-2-methoxycarbonyl-3-methyltetrahydroquinoline (38%): 1H NMR (270 MHz, CDCl3) δ7.00 (td, 1H, J=7.3, 1 Hz), 6.93 (dd, 1H, J=7.3, 1Hz), 6.65 (td, 1H, J=7.3, 1 Hz), 6.58 (dd, 1H, J=7.3, 1 Hz), 4.22 (s, 1H), 3.74 (s, 3H), 3.70 (dd, 1H, J=5.9, 2.1 Hz), 2.79 (dd, 1H, J=15.8, 4.6 Hz), 2.44 (dd, 1H, J=15.8, 6.3 Hz), 2.35 (qddd, 1H, J =6.6, 6.3, 5.9, 4.6 Hz), 1.11 (d, 3H, J=6.6 Hz).

Provenance & Evidence