Abstract: To provide a method for producing an optically active (4E)-5-chloro-2-isopropyl-4-pentenoic acid, a basic amino acid salt thereof or an optically active (4E)-5-chloro-2-isopropyl-4-pentenoic acid ester with high yield and high optical purity by simple operation. An optically active (4E)-5-chloro-2-isopropyl-4-pentenoic acid is obtained by precipitating a basic amino acid salt of optically active (4E)-5-chloro-2-isopropyl-4-pentenoic acid from a solvent solution containing an optical isomer mixture of (4E)-5-chloro-2-isopropyl-4-pentenoic acid and an optically active basic amino acid or a salt thereof, and then the basic amino acid salt of optically active (4E)-5-chloro-2-isopropyl-4-pentenoic acid is subjected to a desalting reaction. Further, an esterification reaction is carried out to obtain an optically active (4E)-5-chloro-2-isopropyl-4-pentenoic acid ester.

Abstract: A difluoroprostacyclin of the following formula (V), its lower alkanol ester or its pharmaceutically acceptable salt: ##STR1## wherein A is an ethylene group, a vinylene group or an ethynylene group, R is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryloxy group, Q is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.

Abstract: A difluoroprostacyclin of the following formula (V), its lower alkanol ester or its pharmaceutically acceptable salt: ##STR1## wherein A is an ethylene group, a vinylene group or an ethynylene group, R is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryloxy group, Q is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.

Abstract: A difluoroprostacyclin of the following formula (V), its lower alkanol ester or its pharmaceutically acceptable salt: ##STR1## wherein A is an ethylene group, a vinylene group or an ethynylene group, R is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryloxy group, Q is a substituted or unsubstituted C.sub.1-10 alkyl group, a substituted or unsubstituted C.sub.1-10 alkenyl group, a substituted or unsubstituted C.sub.1-10 alkynyl group, a substituted or unsubstituted C.sub.3-8 cycloalkyl group, a substituted or unsubstituted aralkyl group, or a substituted or unsubstituted aryl group.