反应详情

One dissolves p-nitrobenzyl α-[3-phenoxymethyl-7-oxo-4-thia-2,6-diazabicyclo[3,2,0]hept-2-en-6-yl]-α-(1-hydroxyethylidene)acetate (940 mg) in dichloromethane (14 ml), cools to -25° C., adds triethylamine (0.61 ml) and methanesulfonyl chloride (0.17 ml), and stirs for 1.5 hours. To the solution, one adds morpholine (0.209 ml), keeps at -25° C. for 1.5 hours, adds bromine (2.2 mmol) dissolved in carbon tetrachloride (2.2 ml) and after 30 minutes at -25° C., adds 5% aqueous sodium hydrogen carbonate, washes with water, dries and evaporates. Purification of the obtained residue (1.134 g) by chromatography over silica gel containing 10% water (100 g) using a mixture of benzene and ethyl acetate (3:1) gives p-nitrobenzyl α-[3-phenoxymethyl-7-oxo-4-thia-2,6-diazabicyclo[3,2,0]hept-2-en-6-yl]-α-(1-morpholino-2-bromoethylidene)acetate (852.6 mg; 69%) and p-nitrobenzyl α -[3-phenoxymethyl-7-oxo-4-thia-2,6-diazabicyclo[3,2,0]hept-2-en-6-yl]-α-methanesulfonyl-α-acetylacetate (1332.2 mg; 12.2%).

1. customcools to -25° C.
2. customevaporates
3. customPurification of the obtained residue (1.134 g) by chromatography over silica gel containing 10% water (100 g)
4. additiona mixture of benzene and ethyl acetate (3:1)