PROCESS FOR THE PREPARATION OF DERIVATIVES OF 7-BETA-SUBSTITUTED 3-CEPHEM-4-CARBOXYLIC ACIDS NOT SUBSTITUTED IN POSITION 3

摘要

The invention relates to a novel advantageous process for the production of compounds of the formula (I) wherein n is 1, R1a is hydrogen or an amino protective group R1A, R1b is hydrogen or an acyl group Ac, or R1a and R1b together are a bivalent amino protective group, R2 is hydroxyl or a radical which, together with the carbonyl grouping -C(=O)-, forms a protected carboxyl group, and the group of the formula -N(R3a) (R3b) is a secondary or tertiary amino group, or a salt thereof with salt-forming groups. The process comprises reaction of the corresponding 3-amino compounds with borohydrides in the presence of acids.