abstract |
The invention relates to compounds of the general formulas in which the radicals R 1 , R 2 , R 3 , R 4 and R 5 have different meanings.n n n The invention further relates to processes for the preparation of these compounds. These compounds are valuable intermediates in the production of cephalosporins of the general formula and the invention further relates to a process for the preparation of such cephalosporins using said intermediates. |