Hydrochloric Acid → HCID 20079405, compound

Participants

Reaction Steps

A solution of 1-methoxycarbonylmethyl-trans-3,4-dimethoxycarbonylpyrrolidine (5 g, 19.31 mmol) in toluene (75 ml) was added dropwise over a 1 hour period to a rapidly stirred solution of potassium-t-butoxide (9 g, 80 mmol) in toluene (250 ml) at 130° C. The mixture was refluxed for 4 hours, cooled to room temperature and concentrated hydrochloric acid (75 ml) added dropwise and stirred for 0.25 hours. The organic phase was extracted with further portions of hydrochloric acid (3×50 ml) and the combined aqueous heated at 110° C. for 16 hours. The solvent was then removed in vacuo, the residue dried and taken up into methanol (saturated with hydrogen chloride, 150 ml). The mixture was stirred at room temperature for 24 hours and the solvent removed under vacuum. The residue was dissolved in water (50 ml), basified to pH>10 with potassium carbonate and extracted with dichloromethane (5×150 ml). The combined extracts were dried (Na2SO4) and the residue remaining after removal of the solvents was chromatographed through silica-gel, using dichloromethane/methanol (93:7) as eluant, to give the title ester as a yellow liquid (0.5 g). An analytical sample was prepared as the hydrogen oxalate salt, mp 134.5°-136.5° C. (propan-2-ol); (Found: C, 47.04; H, 6.20; N, 4.50. C10H17NO4.(CO2H)2 requires C, 47.21; H, 6.27; N, 4.59%); δ (360 MHz, CDCl3) 2.44 (1H, dd, J=9.8 and 3.2 Hz), 2.63 (1H, dd, J=12.7 and 3.2 Hz), 2.77 (1H, d, J=12.7 Hz), 2.80-3.10 (5H, m), 3.11 (3H, s, OCH3), 3.24 (3H, s, OCH3), 3.71 (3H, s, CO2CH3).

Provenance & Evidence