ethyl 2-oxopiperidine-4-carboxylate synthesis

Yield:25410-09-7 94.5%

Reaction Conditions:

with hydrogenchloride in 1,4-dioxane;dichloromethane at 20; for 1 h;

Steps:

21.b; 22.b ethyl 2-oxopiperidine-4-carboxylate

To a solution of the 1-tert-butyl 4-ethyl 2-oxopiperidine-l,4-dicarboxylate (20 g, 74.45 mmol) in DCM (93 mL) was add 4N hydrogen chloride in dioxane (30 mL). The reaction was stirred at room temperature for 1 hour and then the solvent was removed under reduced pressure. The resulting residue was dissolved in DCM and water, then adjusted to PH=8 with saturated aqueous Na₂CO₃ solution, The mixture was extracted with DCM and the combined organic layer was washed with water, brine and dried over anhydrous Na₂S0₄. The organic layer was concentrated in vacuo to afford ethyl 2-oxopiperidine-4-carboxylate (12 g, yield 94.5%). 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 1.25 (t, J = 7.04 Hz, 3 H) 1.84 - 1.93 (m, 1 H) 2.04 - 2.15 (m, 1 H) 2.50 - 2.64 (m, 2 H) 2.75 - 2.86 (m, 1 H) 3.24 - 3.43 (m, 2 H) 4.16 (q, J= 7.04 Hz, 2 H) 6.66 (br. s., 1 H)

References:

WO2014/116504,2014,A1 Location in patent:Page/Page column 88