反应详情

A solution of 3-(5-nitro-pyridin-2-yl)-azetidine-1-carboxylic acid tert-butyl ester (1.22 g, 4.36 mmol) in CH2Cl2 (100 ml) was treated with trifluoroacetic acid (TFA) (15 ml) and then stirred at room temperature for 2 h. After concentration, the raw mixture was digested in CH2Cl2 and washed with saturated aqueous NaHCO3. The aqueous phase was extracted with CH2Cl2 (×3), the combined organic layers dried over Na2SO4 and evaporated. The raw material was next dissolved in THF (80 ml) and the solution cooled to 0° C. Propionyl chloride (460 μl, 5.26 mmol) and triethylamine (735 μl, 5.28 mmol) were next added, the mixture allowed to reach 20° C. and stirred for a further 12 h. It was then diluted with CH2Cl2 and washed successively with 1N aqueous HCl, saturated aqueous NaHCO3 and water. The organic layer was dried (Na2SO4) and evaporated. The residue was chromatographied on silica gel (CH2Cl2:methanol, 49:1) to afford the title compound (880 mg, 85% for two steps) as a brown oil.

1. concentrationAfter concentration
2. washwashed with saturated aqueous NaHCO3
3. extractionThe aqueous phase was extracted with CH2Cl2 (×3)
4. dry with materialthe combined organic layers dried over Na2SO4
5. customevaporated
6. dissolutionThe raw material was next dissolved in THF (80 ml)
7. temperaturethe solution cooled to 0° C
8. customto reach 20° C.
9. stirringstirred for a further 12 h
10. washwashed successively with 1N aqueous HCl, saturated aqueous NaHCO3 and water
11. dry with materialThe organic layer was dried (Na2SO4)
12. customevaporated