Hydrogen Sulfide → 2-(4-Mercaptopiperidin-1-yl)-2-methylpropionic acid methyl ester

Participants

Reaction Steps

H2S gas was bubbled into a solution of 2-methyl-2-(4-oxopiperidin-1-yl)propionic acid methyl ester (1.28 g, 6.42 mmol) in isopropanol (13 mL) for 10 min. The reaction mixture was then sealed, stirred at RT for 18 h and then left standing for 8 days at RT. After this period of time, nitrogen was bubbled into the solution for 10 min, then NaBH4 (364 mg, 9.63 mmol) was added. The reaction mixture was stirred at RT for 10 min and then heated at 80° C. for 2 h. After cooling to RT, volatiles were removed under reduced pressure and the resulting residue was partitioned between diethyl ether and water. The aqueous layer was further extracted with diethyl ether and the combined organic phases were washed with water, followed by brine, then dried over Na2SO4 and concentrated in vacuo. 2-(4-Mercaptopiperidin-1-yl)-2-methylpropionic acid methyl ester (1.497 g, quantitative yield) was obtained as a colorless oil. 1H NMR (CDCl3, 300 MHz): δ 3.71 (3H, s), 3.01-2.85 (2H, m), 2.82-2.64 (1H, m), 2.33-2.14 (2H, m), 2.06-1.94 (2H, m), 1.71-1.58 (2H, m), 1.53-1.48 (1H, m), 1.29 (6H, s).

Provenance & Evidence