NEW MATERIAL:A penicillanic acid derivative of formula I (R1 is H or lower alkyl; R2 is H or OH; R3 are 2W3 OH or lower alkanoyloxy groups, at least two of which are adjacent; when R1 is lower alkyl and R3 is OH, the substitution position of R3 is 3W5 position, and otherwise, it is 2W6 position.) or its salt, and a substituted ureidophenylacetic acid of formula II.
EXAMPLE: 6-[ D(-)-α-[ 3-( 2,3-dihydroxybenzoyl )-1-ureido ]-α-phenylacetamido ] penicillanic acid.
USE: An antibacterial agent and its intermediate, effective remarkably to the bacteria belonging to Pseudomonas genus.
PROCESS: The compound of formula I can be prepared, e.g. by reacting an α-aminophenyl-acetic acid with a benzoyl isocyanate and further reacting the resulting compound of formula II with 6-aminopenicillanic acid or its reactive derivative.