Prostaglandins

A compound of formula (I) ##STR29## where ##STR30## represents one of the divalent cyclic groups ##STR31## the letters a and b indicating in each case the points of attachment of the substituents R.sup.1 and CV(R.sup.2)--NV'R, respectively;

• R.sup.1 is a group --(CH.sub.2).sub.c --B--CH.sub.2 --CO.sub.2 R' in which B is oxygen or sulphur, c is an integer from 3 to 10 and CO.sub.2 R' is carboxy group or a physiologically acceptable amide, ester or salt derivative thereof;
• V and V' either each separately is hydrogen or together are the second bond of a carbon-nitrogen double bond;
• R.sup.2 is hydrogen, a C.sub.1-12 aliphatic hydrocarbon group or a C.sub.1-12 aliphatic hydrocarbon group substituted by a group Ar, OAr or SAr, where Ar represents a phenyl, naphthyl, fluorenyl, dibenzocyclohexyl, dibenzocycloheptyl, pyridyl, benzthiazolyl, dihydrobenzthiazolyl, N-methyldihydro-benzthiazolyl, benzoxazolyl, dihydrobenzoxazolyl or N-methyldihydrobenzoxazolyl group or such a group substituted by one or more substituents selected from C.sub.1-12 alkoxy, halogeno, C.sub.1-12 halogeno-substituted alkyl, sulphamoyl, amino, hydroxyl, nitro and C.sub.1-12 alkyl groups;
• and R is a group --D--R.sup.3, --N.dbd.R.sup. 5 or --NW.G.W' in which D is --NH--, --NH.CS--, --NH.CO--, --NH.CO.CH.sub.2 N(R.sup.6)--, --NH.SO.sub.2 --, --NH.CO.NH--, --NH.CS.NH--, --NH.CO.O-- or --NH.CS.O--, G is --CO-- or --CS-- and W and W' together are a group --(CH.sub.2).sub.d -- in which d is 3, 4 or 5, R.sup.3 is a C.sub.1-12 aliphatic hydrocarbon group, a group Ar or a C.sub.1-12 aliphatic hydrocarbon group substituted by one or more groups selected from Ar, OAr and SAr, R.sup.5 is a C.sub.1-12 aliphatic hydrocarbon group, a group Ar', where Ar' represents a fluorenylidene, dibenzocyclohexylidene, dibenzocycloheptylidene, dihydrobenzthiazolylidene, N-methyl-dihydrobenzthiazolylidene, dihydrobenzoxazolylidene or N-methyl- dihydrobenzoxazolylidene group or such a group substituted on a benzene ring or rings thereof by one or more substituents selected from C.sub.1-12 alkoxy, halogeno, C.sub.1-12 halogeno-substituted alkyl, sulphamoyl, amino, hydroxyl, nitro and C.sub.1-12 alkyl groups, or a C.sub.1-12 aliphatic hydrocarbon group substituted by one or more groups selected from Ar, OAr and SAr, and R.sup.6 is hydrogen, a C.sub.1-12 aliphatic hydrocarbon group, a group Ar or a C.sub.1-12 aliphatic hydrocarbon group substituted by one or more groups selected from Ar, OAr and SAr.