Abstract: Compounds of formula I ##STR1## wherein, R.sub.1 represents hydrogen or methyl,R.sub.2 represents hydrogen or lower alkyl, lower alkenyl, lower alkynyl or cycloalkyl each of which may be unsubstituted or mono- or poly-substituted by amino, mono- or di(lower)-alkylamino, lower acylamino, carboxy, lower alkoxycarbonyl or carbamoyl; a group of formula IIc(CH.sub.2).sub.p --R.sub.5 IIcwherein R.sub.5 represents phenyl or a 5- or 6-membered saturated or unsaturated heterocycle containing one or more heteroatoms selected from O, S and/or N and which may be unsubstituted or mono- or poly-substituted by fluoro, chloro, bromo, amino, mono- or di-(lower)-alkylamino, hydroxy, lower alkoxy, mercapto, alkylthio, phenylthio, sulfamoyl, guanidino, nitro, cyano, lower acylamino, carboxy, alkoxycarbonyl or carbamoyl and p is 0, 1, 2 or 3; or a group of formula ##STR2## wherein R.sub.6, R.sub.7 and R.sub.8 may be the same or different and each represents hydrogen or lower alkyl or R.sub.6 and R.sub.8 and/or R.sub.

Abstract: 6-(1'-fluorethyl)- and 6-(1'-fluoro-1'-methylethyl)-carbapenems such as (5RS,6RS)-1-aza-6-(1(RS)-fluorethyl)-3-(N'-dimethyl-N'-methylamidinomethyl thio)-7-oxobicyclo[3.2.0]hept-2-ene-2-carboxylic acid which are useful as chemotherapeutic agents in particular as anti-bacterially active anti-biotics.