Abstract: Prostaglandin I.sub.2 analogues of the formula: ##STR1## [wherein the symbol between the carbon atoms in positions 5 and 6 represents a single or double bond, Y represents ethylene or trans-vinylene, R.sup.1 represents hydrogen, alkyl of 1 to 12 carbon atoms, aralkyl of 7 to 12 carbon atoms, cycloalkyl of 4 to 7 carbon atoms optionally substituted by alkyl of 1 to 4 carbon atoms, phenyl optionally substituted by chlorine, trifluoromethyl, alkyl of 1 to 4 carbon atoms or phenyl, a --C.sub.m H.sub.2m COOR.sup.7 group (wherein m represents an integer of from 1 to 12 and R.sup.7 represents alkyl of 1 to 4 carbon atoms), a --C.sub.n H.sub.2n OR.sup.8 group (wherein n represents an integer of from 2 to 12 and R.sup.8 represents hydrogen or alkyl of 1 to 4 carbon atoms) or a ##STR2## group (wherein R.sup.9 and R.sup.10 each represent alkyl of 1 to 4 carbon atoms and n is as hereinbefore defined), R.sup.2 represents hydrogen or a hydroxy-protecting group, R.sup.

Abstract: The present invention relates to prostaglandin analogues of the general formula: ##STR1## [wherein X represents cis or trans-vinylene or ethylene, R represents ##STR2## R.sup.1 represents a hydrogen atom or a straight- or branched-chain alkyl group containing from 1 to 12 carbon atoms, R.sup.2 represents a hydrogen atom or a methyl group, R.sup.3 represents a straight- or branched-chain alkylene group containing from 1 to 7 carbon atoms and R.sup.4 represents a cycloalkyl group containing from 5 to 7 carbon atoms, a grouping of the formula: ##STR3## (wherein R.sup.5 and R.sup.6, which may be the same or different, each represent a hydrogen atom or halogen atom, a trifluoromethyl group or a straight- or branched-chain alkyl group containing from 1 to 4 carbon atoms), or a grouping of the formula: ##STR4## (wherein R.sup.5 and R.sup.6 are as hereinbefore defined), or R.sup.3 and R.sup.