Methyl chloroformate → methyl (1aRS,7bSR)-5-[N-(methoxycarbonyl)-N-(4-fluoro-2-nitrobenzene-sulfonyl)amino]-1,1a,2,7b-tetrahydro-cyclopropa[c]chromene-4-carboxylate

Participants

Reaction Steps

A solution of methyl (1aRS,7bSR)-5-(4-fluoro-2-nitrobenzenesulfonylamino)-1,1a,2,7b-tetrahydro-cyclopropa[c]chromene-4-carboxylate (Intermediate 112, 0.25 g) in THF (10 mL) was added dropwise with stirring to a cooled suspension of sodium hydride (0.1 g) in THF (5 mL) at 0° C. On completion of the addition, the mixture was stirred at room temperature for 30 minutes. Methyl chloroformate (0.3 g) was added dropwise and the mixture was stirred at room temperature for 1.5 hours. Saturated aqueous sodium bicarbonate was added and the mixture was extracted with ethyl acetate, dried (Na2SO4) and filtered. The filtrate was evaporated to dryness and the residue was purified by chromatography on silica, eluting with a mixture of ethyl acetate and petroleum ether to give methyl (1aRS,7bSR)-5-[N-(methoxycarbonyl)-N-(4-fluoro-2-nitrobenzenesulfonyl)amino]-1,1a,2,7b-tetrahydrocyclopropa-[c]chromene-4-carboxylate (0.2 g) as a white solid.

Provenance & Evidence