反应详情

To a stirred solution of ethyl 1-methylpiperidine-4-carboxylate (3.66 g, 0.0214 mole) in 20 mL of anhydrous ether at -78° under nitrogen gas was added, dropwise, 2 equivalents of diisobutylaluminum hydride (46 mL of a 20% by weight solution in hexane). After the addition (30 min.), the mixture was stirred at -78° for 2 hours. Fifty mL of water was slowly added to decompose the excess hydride. The mixture was stirred at room temperature for one hour. The ether solution was decanted and the aqueous solution was extracted with methylene chloride (3×50 mL). The combined extracts were evaporated in vacuo to give 1-methyl-4-piperidinecarboxaldehyde as a colorless liquid (2.361 g, 86.8%): IR (neat) 2940, 2850, 2790, 2740, 2680, 1725, 1440, 1450, 1380, 1280, 1145, 1090, 1070, 1040, 970, 930 and 760 cm-1 ; NMR (CDCl3) δ1.85 (m, 5H), 2.05 (m, 2H), 2.22 (s, 3H), 1.65 (m, 2H) and 9.67 (s, 1H). The NMR spectrum clearly indicated the product was the aldehyde (peak at δ9.67).

1. additionAfter the addition (30 min.)
2. stirringThe mixture was stirred at room temperature for one hour
3. customThe ether solution was decanted
4. extractionthe aqueous solution was extracted with methylene chloride (3×50 mL)
5. customThe combined extracts were evaporated in vacuo