To a cooled (5 ??C) and stirred mixture of potassium 2-methyl-2-propoxide (29.7 g,0.27 mol) was added a solution of ethyl [A/-((1,1-dimethylethoxy)carbonyl),A/-(2-oxopropyl)]glycinate (65 g, 0.25 mol) in ethyl ether (200 ml) over a period of 1.5 h. The re- sulting mixture was stirred for an additional 3 h, and the formed precipitate was filtered offand washed with ethyl ether (2 x 100 ml). The solid was dissolved in water (150 ml), andacetic acid was added to adjust the pH to 4. The product was filtered, washed with water (2x 50 ml) and air dried to furnish 1 -[(1,1 -dimethylethoxy)carbonyl]-3,5-dioxopiperidine (28 g,52 %).>xxN'TOHPLC-MS: m/z: 158 (M+H-56).1H-NMR (DMSO-d6): 81.48 (9H, s), 4.03 (4H, s), 5.38 (1 H, s).
