Diastereomeric 7-ureidoacetyl cephalosporins. II. 7.BETA.[[[(Aminocarbonyl) amino]-2-thienylacetyl] amino]-7-methoxy-3-[[(1-methyl-1H-tetrazol-5-yl) thio] methyl]-8-oxo-5-thia-1-azabicyclo [4.2.0] oct-2-ene-2-carboxylic acid.

Abstract
The synthesis and antibacterial activity in vitro of 7-methoxylated cephalosporins having a thienylureidoacetyl or a thienylglycyl C-7 side-chain are described. Acylation of 7.beta.-amino-7-methoxycephems with a novel 2-aminooxazolone hydrochloride under neutral conditions gave the thienylureidoacetyl derivatives in good yield with retention of configurations. 7.beta.-[[D-[(Aminocarbonyl)amino]-2-thienylacetyl]amino]-7-methoxy-3-[[(1-methyl-1H-tetrazol-5-yl)thio]methyl]-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid Na salt (SQ 14,359) had a broad spectrum of antibacterial activity in vitro, particularly against .beta.-lactamase-producing organisms.