Novel compounds have a formula (I)
wherein
represents a bicyclo (2,2,1) hept-2Z-ene, bicyclo (2,2,1) heptane, 7-oxabicyclo (2,2,1) hept-2Z-ene, 7-oxabicyclo (2,2,1) heptane, bicyclo (2,2,2) oct-2Z-ene or bicyclo (2,2,2) octane substituted at the 5-position by the group R 1 and at the 6-position by the group C(R 2 )=NR, a 6,6-dimethyl-bicyclo (3,1,1) heptane substituted at the 5- position by the group R' and at the 6-position by the group C(R 2 )=NR or at the 5-position by the group C(R 2 )=NR and at the 6-position by the group R 1 , a cyclohex-1-ene or cyclohexane substituted at the 4-position by the group R 1 and at the 5-position by the group C(R 2 )=NR, or a 1-hydroxycyclopentane substituted at the 2-position by the group R 1 and at the 2-position by the group C(R 2 )=NR, R 1 is a 6-carboxyhex-2-enyl group or a modification thereof as defined herein, R 2 is hydrogen, an aliphatic hydrocarbon group or an aliphatic hydrocarbon group substituted directly or through an oxygen or sulphur atom by an aromatic group, and R is a group -OR 3 , -OR 4 , -A-R 3 or -N=R 5 in which A is -NH-, -NH.CO-, -NH.CO.CH 2 N(R 6 )-, -NH.SO 2 -, -NH.CO.NH or -NH.CS.NH- and wherein R 3 is an aliphatic hydrocarbon group, an aromatic group or an aliphatic hydrocarbon group substituted directly or through an oxygen or sulphur atom by an aromatic group, R 4 is an aliphatic hydrocarbon group which is substituted through an oxygen atom by an aliphatic hydrocarbon group which is itself substituted by an aromatic group, R 5 is an aliphatic hydrocarbon group, an aromatic group or an aliphatic hydrocarbon group substituted directly or through an oxygen or sulphur atom by an aromatic group, and R 6 is hydrogen, an aliphatic hydrocarbon group, an aromatic group or an aliphatic hydrocarbon group substituted directly or through an oxygen or sulphur atom by an aromatic group, with the proviso that when R is a group -OR 3 , -NH.COR 3 or-NH.CO.NHR3 then
excludes bicyclo (2,2,1) hept-2Z-enes and bicyclo (2,2,1) heptanes. The compounds are of value for use in phar. maceutical compositions particularly in the context of the inhibition of thromboxane activity.