反应详情

In a 25 ml two necked round bottom flask equipped with a dean stark separator, a reflux condenser, a thermometer, a magnetic stirrer and an inert gas supply, 0.90 g (4.47 mmol) (3R,4S,5R)-5-amino-3,4-dihydroxy-cyclohex-1-enecarboxylic acid ethyl ester was suspended in 9.0 ml 3-pentanon, 0.32 ml (4.92 mmol) methanesulfonic acid was added, the mixture was heated to reflux, with a dean stark separator for 2 hours. The reaction mixture was cooled to r.t., diluted with 9.0 ml ethyl acetate and the mixture was extracted with 9.0 ml 1M aqueous sodium hydrogen carbonate solution. The organic layer was dried over about 1 g sodium sulfate and filtered. The filter cake was washed with about 9 ml of ethyl acetate and the combined filtrates were evaporated in a rotary evaporator at 40° C./10 mbar to yield as the crude intermediate 1.05 g (3aR,7R,7aS)-7-amino-2,2-diethyl-3a,6,7,7a-tetrahydro-benzo[1,3]dioxole-5-carboxylic acid ethyl ester.

1. temperaturethe mixture was heated
2. temperatureto reflux, with a dean stark separator for 2 hours
3. extractionthe mixture was extracted with 9.0 ml 1M aqueous sodium hydrogen carbonate solution
4. dry with materialThe organic layer was dried over about 1 g sodium sulfate
5. filtrationfiltered
6. washThe filter cake was washed with about 9 ml of ethyl acetate
7. customthe combined filtrates were evaporated in a rotary evaporator at 40° C./10 mbar