反应详情

To a stirred and iced solution of potassium hydroxide (7.3 g; 130 mmol) in methanol (30 ml) was added hydroxylammonium chloride (6.9 g; 100 mmol). After stirring at 0° C. for further 30 minutes a solution of ethyl 1-methoxycarbonyl-3-oxopiperidine-4-carboxylate ethylene acetal (6.8 g; 25 mmol) in ethanol (20 ml) was added, and the mixture was left at 8° C. for 8 days. Upon addition of glacial acetic acid (15 ml) and filtration the filtrate was evaporated in vacuo to give a treacly mass. CC [silica gel (Woelm 0.063-0.1 mm): 250 g; eluents: ethyl acetate to which methanol (15-26%) and formic acid (1%) was added] afforded IXa (1.9 g; 29%) was a crystalline and TLC-pure substance [RF : 0.23; eluent: ethyl acetate-methanol-formic acid (90:9:1)]. An analytical sample was recrystallized (ethanol-benzene) to give IXa as colourless crystals, m.p. 150.0°-152.0° C. IR (KBr): 3700-3350 (m), 3280 (m), 3210 (s), 3055 (w), 3000-2870 (several bands, w-m), 1690 (s), 1640 (s), 1550 (w) cm-1. 1H NMR [CDCl3 -DMSO-d6 (1:1): δ10.5-10.1 (1H, m), 4.9-4.3 (1H, m), 3.93 (s), 3.60 (s), and 4.1-3.1 (m) (a total of 11H), 2.8-2.6 (1H, m), 2.2-1.8 (2H, m).

1. additionwas added
2. customwas evaporated in vacuo
3. customto give a treacly mass
4. customafforded IXa (1.9 g; 29%)
5. customAn analytical sample was recrystallized (ethanol-benzene)
6. customto give IXa as colourless crystals, m.p. 150.0°-152.0° C