反应详情

A solution of 2,3-dihydro-1-oxo-1H-pyrrolizine (16.1 g, 0.133 m); J. Org. Chem., 27 2468 (1962) ) in dried dimethylsulfoxide (60 ml) is added dropwise over ca. 10 minutes to a mixture of methylenetriphenylphosphorane (from methyl triphenylphosphonium bromide (57.2 g, 0.16 m), sodium hydride 60% dispersion (6.4 g, 0.16 m) and dimethylsulfoxide (256 ml) in the standard fashion (J. Org. Chem., 28 1128 (1963)) at ambient temperatures. After stirring for ca 2 hours, the mixture is heated in an oil-bath set at 70° C. for ca 30 minutes, and let cool. After stirring overnight at ambient temperatures, the mixture is poured into 1200 ml of ice-water, extracted 4×400 ml of ether, the ether layers washed 3×400 ml of water, dried and concentrated to a residue. The residue is extracted well with hexane, the filtered hexane extracts concentrated and distilled to yield 2,3-dihydro-1-methylene-1H-pyrrolizine.

1. temperaturethe mixture is heated in an oil-bath
2. waitset at 70° C. for ca 30 minutes
3. temperaturelet cool
4. stirringAfter stirring overnight at ambient temperatures
5. extractionextracted 4×400 ml of ether
6. washthe ether layers washed 3×400 ml of water
7. customdried
8. concentrationconcentrated to a residue
9. extractionThe residue is extracted well with hexane
10. concentrationthe filtered hexane extracts concentrated
11. distillationdistilled