反应详情

The carboxylic acid (1.97 g; prepared in reference example 24) and pyridine hydrochloride (12 g) were heated to 180°-190° C. The mixture was reacted for 3.5 hr. The reaction mixture was cooled and then dissolved in water. The solution was extracted with ethyl acetate. The extract was washed with water, dried over anhydrous magnesium sulfate and then evaporated. The residue was purified by column chromatography on silica gel (n-hexane:ethyl acetate=3:1→1:1). The obtained crystals were washed with a mixture of n-hexane and ethyl acetate (3:1→1:1) to give the title compound (751 mg) having the following physical data.

1. customThe mixture was reacted for 3.5 hr
2. temperatureThe reaction mixture was cooled
3. extractionThe solution was extracted with ethyl acetate
4. washThe extract was washed with water
5. dry with materialdried over anhydrous magnesium sulfate
6. customevaporated
7. customThe residue was purified by column chromatography on silica gel (n-hexane:ethyl acetate=3:1→1:1)
8. washThe obtained crystals were washed with a mixture of n-hexane and ethyl acetate (3:1→1:1)