| 摘要 |
The invention relates to a new process for the production of intermediates for the synthesis of caephalosporin of formula (I) wherein R<SUB>1</SUB>, R<SUB>2 </SUB>and R<SUB>3</SUB>, independently of one another, are alkyl, alkenyl, aryl, hydroxy(C<SUB>1-6</SUB>)alkyl, carbamoyl-(C<SUB>1-6</SUB>)alkyl, amino-(C<SUB>1-6</SUB>)alkyl, acylamino-(C<SUB>1-6</SUB>)alkyl or carboxy(C<SUB>1-6</SUB>)alkyl, or wherein R<SUB>2 </SUB>and R<SUB>3 </SUB>together with the adjacent nitrogen atom, form an alicyclic 5- to 8-membered heterocyclic ring, and R<SUB>1 </SUB>signifies alkyl, alkenyl or aryl. The process according to the invention is notable in that the formation of undesired by-products, especially Delta2-analogous compounds of formula (I), is greatly reduced.
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