Prostacyclins and process for production thereof

Prostacyclins expressed by the following formula (1) ##STR15## wherein a symbol between the 2-position and 3-position indicates a single bond or double bond;

• G indicates --CO.sub.2 R.sup.5 or --CONR.sup.6 R.sup.7 in which R.sup.5 is a hydrogen atom, C.sub.1 -C.sub.10 alkyl group, substituted or unsubstituted phenyl group, substituted or unsubstituted C.sub.5 -C.sub.8 alicyclic group, substituted or unsubstituted phenyl(C.sub.1 -C.sub.2)alkyl group, tri(C.sub.1 -C.sub.7)-hydrocarbon-silyl group, or one equivalent cation comprising alkali metal cations or ammonium cations, R.sup.6 and R.sup.7 are identical or different and each represents a hydrogen atom, or C.sub.1 -C.sub.10 alkyl group, or R.sup.6 and R.sup.7 are, together with substituted or unsubstituted five to six-membered rings, selected from the group consisting of 1-pyrrolidyl, thiazolyl, 1-piperidyl, morpholyl, piperazyl and 5,6-dihydrophenonthridyl, R.sup.1 indicates a hydrogen atom, or methyl group;
• R.sup.2 indicates an unsubstituted C.sub.3 -C.sub.8 alkyl group, substituted or unsubstituted C.sub.5 -C.sub.8 alicyclic group, or substituted C.sub.1 -C.sub.5 alkyl group substituted by substituents selected from phenyl, phenoxy, C.sub.1 -C.sub.6 alkoxy and C.sub.5 -C.sub.6 cycloalkyl group, which substituents may be substituted;
• and R.sup.3 and R.sup.4 are identical or different, each indicating a hydrogen atom, C.sub.2 -C.sub.7 acyl group, tri(C.sub.1 -C.sub.7)hydrocarbon-silyl group, or a group which forms an acetal linkage together with the oxygen atom of the hydroxyl group;
• and the substituents on the substituted phenyl groups, C.sub.5 -C.sub.8 alicyclic group, phenyl-(C.sub.1 -C.sub.2)alkyl group, five to six-membered ring, phenoxy, C.sub.1 -C.sub.6 alkoxy, and C.sub.5 -C.sub.6 cycloalkyl are a halogen group, hydroxy group, C.sub.2 -C.sub.7 acyloxy group, C.sub.1 -C.sub.4 alkyl group which may be substituted by a halogen atom, C.sub.1 -C.sub.4 alkoxy group which may be substituted with a halogen atom, nitrile group, carboxyl group, or C.sub.1 -C.sub.6 alkoxycarbonyl group.