Abstract: Cyclopentane derivatives of the formula: ##STR1## wherein R.sup.1 represents alkyl of 1 through 4 carbon atoms, R.sup.2 represents hydrogen or alkyl of 1 through 3 carbon atoms, R.sup.3 represents alkoxy of 3 through 6 carbon atoms, or alkoxyalkyl in which alkoxy and alkyl moieties each contain 1 through 4 carbon atoms, R.sup.4 represents hydrogen or alkyl of 1 through 12 carbon atoms, R.sup.5 represents hydrogen or alkyl of 1 through 4 carbon atoms or a carboxylic acyl group, A represents carbonyl or a group --CH(OR.sup.5)-- wherein R.sup.5 is as hereinbefore defined, and X represents ethylene or trans-vinylene, possess pharmacological properties, for example the production of hypotension, broncodilation, inhibition of gastric acid secretion, and stimulation of uterine contraction.

Abstract: Cyclopentane derivatives of the prostaglandin type of the formula: ##SPC1##(wherein R.sup.1 represents hydrogen or lower alkyl, R.sup.2 represents alkyl of 1 to 10 carbon atoms, the symbols R.sup.3 are the same and represent hydrogen, lower alkyl, lower alkenyl, phenyl(lower)alkyl or lower alkanoyl, R.sup.