Studies on 6 alpha-substituted penicillins. II. Synthesis and structure-activity relationships of 6 beta-(2-aryl-2-sulfoacetamido)-6 alpha-methoxy penicillanic acids.

The synthesis and antibacterial activity of 6 alpha-methoxysulbenicillin analogues (2) are described. Structure-activity studies of these derivatives bearing hydrophilic substituents in the phenyl ring led to the identification of disodium 6 beta-[D-2-(3,4-dihydroxyphenyl)-2-sulfoacetamido]-6 alpha-methoxypenicillanate (2m) as a compound with potent activity against Pseudomonas aeruginosa including beta-lactamase producing strains. Additional substitution of 2m gave derivatives 2p, 2q, 2r, with a further improvement in activity against Gram-negative bacteria.