Acetylcysteamine → 4-nitrobenzyl (5R,6S)-3-(2-acetamidoethylthio)-6-[1-methyl-1-(4-nitrobenzyloxycarbonyloxy)ethyl]-7-oxo-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-nitrobenzyl(2R,5R,6S)-3,7-dioxo-6-[1-methyl-1-(4-nitrobenzyloxycarbonyloxy)-ethyl]-1-azabicyclo[3.2.0]heptane-2-carboxylate (47.8 mg) and 4-(N,N-dimethylamino)pyridine (1.08 mg) in acetonitrile (2.39 ml) was added dropwise a solution of di-isopropylethylamine (18.5 μl) in acetonitrile (166.5 μl) followed by addition of a solution of diphenyl chlorophosphate (19.2 μl) in acetonitrile (172.8 μl) at 0° C. After stirring for an hour at 0° C., a solution of di-isopropylethylamine (61.5 μl) in acetonitrile (553.5 μl) was added followed by addition of a solution of N-(2-mercaptoethyl)-acetamide (11.05 mg) in acetonitrile (99.45 μl) at -15° C. The mixture was allowed to stand overnight at -15° C. The resulting solution was diluted with ethyl acetate (34 ml) and washed with dilute aqueous sodium chloride and saturated aqueous sodium chloride. After drying over magnesium sulfate, the ethyl acetate extract was filtered and evaporated in vacuo. The residual oil (76.4 mg) was chromatographed on silica gel (1.5 g) eluting with a mixture of methylene chloride and acetone (20:1 to 2:1) to give 4-nitrobenzyl(5R,6S)-3-(2-acetamido-ethylthio)-6-[1-methyl-1-(4-nitrobenzyloxycarbonyloxy)ethyl]-7-oxo-1-aza-bicyclo[3.2.0]hept-2-ene-2-carboxylate (54.0 mg) as an amorphous solid.

Provenance & Evidence