反应详情

A mixture of intermediate 2 (10.07 g), sodium ethoxide (5.42 g) and molecular sieves (45 g) in ethanol (150 ml) was stirred for 30 minutes at RT. Intermediate 1 (9.1 g) was added and the reaction mixture was stirred and refluxed for 10 hours. The reaction mixture was cooled, filtered and the filtrate evaporated. The residue was purified by column chromatography on silica gel (eluent: CH2Cl2 /CH3OH 95/5). The pure fractions were collected and the solvent evaporated, yielding 11.6 g (74%) of ethyl 4- [5-(4-amino-5-chloro-2,3-dihydro-7-benzofuranyl)- 1,2,4-oxadiazol-3-yl]-1-piperidinecarboxylate (intermediate 3; mp. 162.4° C.).

1. stirringthe reaction mixture was stirred
2. temperaturerefluxed for 10 hours
3. temperatureThe reaction mixture was cooled
4. filtrationfiltered
5. customthe filtrate evaporated
6. customThe residue was purified by column chromatography on silica gel (eluent: CH2Cl2 /CH3OH 95/5)
7. customThe pure fractions were collected
8. customthe solvent evaporated