反应详情

27 g of N-bromosuccinimide were added portionwise to an ice-cold solution of 30 g of t-butyl 7-formamido-3-methyl-3-cephem-4-carboxylate-1-oxide in 1600 ml of a 1:1 mixture of acetic acid and dichloromethane under exposure to light of two tungsten lamps of 150 W over 3 hours. After a total exposure of 4 hours, the reaction mixture was then washed 3 times with water, a saturated solution of sodium bicarbonate and again with water. The organic phase was treated with activated carbon, dried over magnesium sulfate and evaporated to dryness after filtration. The residue was subjected to preparative high pressure chromatography using a 4:1 mixture of dichloromethane and acetone as eluent to obtain by evaporation to dryness of the suitable fractions 10.7 g of t-butyl 3-bromomethyl-7-formamido-3-cephem-4-carboxylate-1-oxide having the following characteristics:

1. washAfter a total exposure of 4 hours, the reaction mixture was then washed 3 times with water
2. additionThe organic phase was treated with activated carbon
3. dry with materialdried over magnesium sulfate
4. customevaporated to dryness
5. filtrationafter filtration
6. additiona 4:1 mixture of dichloromethane and acetone as eluent