反应详情

To a solution of 137 mg of 6-formyl-N-phenylimidazo[1,2-a]pyridine-2-carboxamide (Intermediate 8) in 5 mL of toluene are added 45 μL of ethylene glycol, 169 mg of para-toluenesulfonic acid and molecular sieves. The mixture is refluxed for 24 hours in a round-bottomed flask equipped with Dean-Stark apparatus, and then cooled, filtered, diluted with 100 mL of dichloromethane and washed with 2N sodium hydroxide and with water. The organic phases are dried and concentrated to dryness to give a mixture of the starting material and of the expected product, which is redissolved in 5 mL of methanol containing 410 μL of ethylene glycol, 130 mg of para-toluenesulfonic acid and molecular sieves. The mixture is heated for 16 hours at reflux and then cooled, filtered and concentrated to dryness. The residue is chromatographed on a silica cartridge, eluting with a 70/30 mixture of dichloromethane and ethyl acetate to give 53 mg of 6-(1,3-dioxolan-2-yl)-N-phenylimidazo[1,2-a]pyridine-2-carboxamide in the form of a white solid.

1. temperatureThe mixture is refluxed for 24 hours in a round-bottomed flask
2. customequipped with Dean-Stark apparatus
3. temperaturecooled
4. filtrationfiltered
5. additiondiluted with 100 mL of dichloromethane
6. washwashed with 2N sodium hydroxide and with water
7. customThe organic phases are dried
8. concentrationconcentrated to dryness
9. customto give
10. additiona mixture of the starting material