Disclosed are 6-(1'-hydroxyethyl)-3-substituted amino-1-azabicyclo�3.2.0!hept-2-en-7-one-2-carboxylic acids (I): ##STR1## wherein R' and R" are independently selected from H, substituted and unsubstituted alkyl and aralkyl groups, or together form a substituted or unsubstituted cyclic group. Such compounds and their O- and carboxyl derivatives are useful as antibiotics. Also disclosed are processes for the preparation of such compounds, pharmaceutical compositions comprising such compounds and methods of treatment comprising administering such compounds and compositions when an antibiotic effect is indicated.