反应详情

A mixture of 2-amino-5-picoline (Aldrich; 5.028 g), 1,3-dichloroacetone (Aldrich; 5.893 g), and 1,2-dimethoxyethane (Aldrich; 43 mL) is stirred for 1 h at 55° C., at which time ethanol (47 mL) is added and the mixture is stirred for 2.75 h at reflux. The mixture is then concentrated under reduced pressure and partitioned between dichloromethane and saturated aq. sodium bicarbonate. The combined organic layers are washed with brine, dried with MgSO4, and concentrated under reduced pressure. The residue is chromatographed on silica gel using methanol/dichloromethane (1/99) and the appropriate fractions are combined and concentrated to give, after crystallization from ethyl acetate, 0.411 g of 2-(chloromethyl)-6-methylimidazo[1,2-a]pyridine. Methanol is added to the filtrate, which is then concentrated to a reduced volume. The addition of hexane gives an additional 1.50 g of 2-(chloromethyl)-6-methylimidazo[1,2-a]pyridine in two crops; mp 88-89.25° C.; ms m/z 180; IR (mineral oil) 796, 705, 699, 1343, 1510 cm-1 ; 1H NMR (CDCl3) 8 2.32, 4.76, 7.03, 7.47, 7.53, 7.86.

1. additionis added
2. temperatureat reflux
3. concentrationThe mixture is then concentrated under reduced pressure
4. custompartitioned between dichloromethane and saturated aq. sodium bicarbonate
5. washThe combined organic layers are washed with brine
6. dry with materialdried with MgSO4
7. concentrationconcentrated under reduced pressure
8. customThe residue is chromatographed on silica gel
9. concentrationconcentrated
10. customto give
11. customafter crystallization from ethyl acetate, 0.411 g of 2-(chloromethyl)-6-methylimidazo[1,2-a]pyridine
12. additionMethanol is added to the filtrate, which
13. concentrationis then concentrated to a reduced volume
14. additionThe addition of hexane