Disclosed are compounds of formula ##STR1## wherein R is OR' and R' is aryl-lower alkyl, biaryl-lower alkyl, lower alkyl or cycloalkyl-lower alkyl; or R is arylsulfonylamido; n is 1, 2 or 3; m is 1, 2 or 3; Y is vinylene, ethylene or methyleneoxy; a stereoisomer or optical isomer thereof; and their pharmaceutically acceptable esters or salts; which are useful as thromboxane synthetase inhibitors and thromboxane receptor antagonists.