反应详情

A mixture of 103.2 g of dicyclohexylcarbodiimide, 43.5 g of t-butanol and 1.1 g of cuprous chloride was stored for 3 days at room temperature and the resulting compound was dissolved into 200 ml of dichloromethane. The solution was added dropwise to a stirred suspension of 35 g of 7-benzamido-3-methyl-3-cephem-4-carboxylic acid-1-oxide in 500 ml of dichloromethane and after stirring at room temperature for 24 hours, the obtained N,N'-dicyclohexyl urea was separated by filtration and washed with dichloromethane. The combined filtrate and washing liquid were extracted with a 2 N hydrochloric acid solution, a saturated sodium bicarbonate solution and twice with water. The dichloromethane was evaporated under vacuo and toluene was added to the residue. The obtained crystals were filtered off and were washed with toluene. After crystallization from a mixture of dichloromethane and toluene, 19.6 g of t-butyl 7-benzamido-3-methyl-3-cephem-4-carboxylate-1-oxide were obtained having the following characteristics:

1. customthe obtained N,N'-dicyclohexyl urea was separated by filtration
2. washwashed with dichloromethane
3. washThe combined filtrate and washing liquid
4. extractionwere extracted with a 2 N hydrochloric acid solution
5. customThe dichloromethane was evaporated under vacuo and toluene
6. additionwas added to the residue
7. filtrationThe obtained crystals were filtered off
8. washwere washed with toluene
9. customAfter crystallization
10. additionfrom a mixture of dichloromethane and toluene