Diethyl Ether → 8-Oxo-2,2,5,7-tetramethyl-7-(1-o-nitrobenzylcarbonyldioxymethyl)-3-oxa-1-azabicyclo[4.2.0]octane

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Reaction Steps

Under anhydrous conditions at 0° C. a solution of 8-oxo-2,2,5,7-tetramethyl-7-(hydroxymethyl)-3-oxa-1-azabicyclo[4.2.0]octane (60 mg) in 0.6 ml ether is treated with powdered potassium hydroxide (19 mg). After a period of 15 minutes, o-nitrobenzyl chloroformate (65 mg) is added to the reaction mixture. Stirring is continued at 25° C. for an additional 15 hours. The mixture is partitioned between 1 M pH 7 phosphate buffer and more ether. The ether phase is washed with water and brine, dried over magnesium sulfate and filtered. Evaporation of the filtrate under reduced pressure gives a colorless oil. Purification by preparation thick-layer chromatography on silica gel developing with 1:9 ethylacetate/benzene gives 8-oxo-2,2,5,7-tetramethyl-7-(o-nitrobenzylcarbonyldioxymethyl)-3-oxa-1-azabicyclo-[4.2.0]octane as a mixture of diastereomers.

Provenance & Evidence