Oxabicycloalkane herbicides

A compound of the formula Ig ##STR44## wherein R is a hydrogen atom;

• or a straight-chain alkyl group containing from 1 to 6 carbon atoms;
• R.sup.1 is a hydrogen atom;
• an alkyl group containing from 1 to 6 carbon atoms;
• an alkyl group containing from 1 to 6 carbon atoms substituted by 1 to 3 halogen atoms, each having an atomic number of from 9 to 35, inclusive, a hydroxy group, a cyano group or an alkoxy group containing from 1 to 4 carbon atoms, a C.sub.1-6 alkylthio group, a C.sub.6-10 arylthio group, a C.sub.7-11 aralkylthio group, an azido group, a C.sub.1-6 alkoxycarbonyl group, a hydroxycarbonyl group, a phosphoryl group, a phosphoryloxy group, a carbamoyl group or a thiocarbamoyl group substituted by hydrogen or 1 or 2 alkyl groups containing from 1 to 6 carbon atoms;
• an aryl or aralkyl group, each containing from 6 to 10 carbon atoms, and 1 or 2 carbons in the alkyl portion;
• an aryl or aralkyl group containing from 6 to 10 carbon atoms, and 1 to 2 carbons in the alkyl portion, ring-substituted by one or more substituents independently selected from a halogen atom, each having an atomic number of from 9 to 35, inclusive, an alkyl or alkoxy group containing from 1 to 2 carbon atoms, or an alkyl or alkoxy group containing from 1 to 2 carbon atoms substituted by one or more halogen atoms, each having an atomic number of from 9 or 17;
• R.sup.1 is a group --CO.sub.2 R.sup.6 or --CON(R.sup.6).sub.2 in which R.sup.6 is a hydrogen atom, or an alkyl group containing from 1 to 6 carbon atoms;
• each R.sup.3 is independently selected from a hydrogen atom;
• a chlorine atom;
• a bromine atom;
• an alkyl group containing from 1 to 4 carbon atoms;
• an alkyl group containing from 1 to 4 carbon atoms substituted by 1 to 3 halogen atoms, each having an atomic number of from 9 to 35, inclusive;
• or two of R.sup.3 when located on adjacent carbon atoms together form an epoxide ring or a carbon-carbon bond;
• R.sup.4 is a hydrogen atom;
• an alkyl group containing from 1 to 4 carbon atoms;
• or an alkyl group containing from 1 to 4 carbon atoms substituted by 1 to 3 halogen atoms having an atomic number of from 9 to 35, inclusive;
• each R.sup.5 is independently selected from a hydrogen atom;
• an alkyl group containing from 1 to 4 carbon atoms;
• an alkyl group containing 1 to 4 carbon atoms substituted by 1 to 3 halogen atoms having an atomic number of from 9 to 35, inclusive;
• or a hydroxy group;
• and stereoisomeric forms or mixtures thereof, with the proviso that R and R.sup.1 are not both hydrogen atoms and when R is methyl R.sup.3, R.sup.4 and R.sup.5 all are hydrogen atoms, then R.sup.1 is other than isopropyl.