反应详情

Ethylene glycol (5 ml) and a catalytic amount of p-toluenesulfonic acid were added to 4-formyl-piperidine-1-carboxylic acid benzyl ester from Example E33.2 (5.6 g, 22.6 mmol) in toluene (100 ml) and the mixture was heated at reflux under Dean and Stark conditions for 2.5 h. Solvents were removed in vacuo and the residue was redissolved in EtOAc, washed with saturated NaHCO3 then brine, dried and concentrated in vacuo. The residue was purified by flash chromatography on silica gel (eluant; 50% EtOAc:50% pet. ether) to yield the title compound (5.14 g, 78%).

1. temperaturethe mixture was heated
2. temperatureat reflux under Dean and Stark conditions for 2.5 h
3. customSolvents were removed in vacuo
4. dissolutionthe residue was redissolved in EtOAc
5. washwashed with saturated NaHCO3
6. dry with materialbrine, dried
7. concentrationconcentrated in vacuo
8. customThe residue was purified by flash chromatography on silica gel (eluant; 50% EtOAc:50% pet. ether)