BICYCLOOCTANE DERIVATIVES AND THEIR PRODUCTION AND USE

(1) A compound of the formula: wherein X1 is a free or an esterified carboxyl group, or a group of the formula: (Ra and Rb are each independently a hydrogen atom, a C1-C4 alkyl group, a C3-C7 cycloalkyl group, a benzyl group, a phenyl group, a phenyl group substituted with a halogen atom or a C1-C4 alkyl group, or, when taken together with the adjacent nitrogen atom to which they are attached, they represent a 5 to 7 membered saturated heterocyclic grou), y1 is a group of the formula: (2) (R6 is a hydrogen atom or C1-C4 alkyl group), (R6 is as defined above), or -C?C- , R1 is a hydrogen atom, a hydroxyl group or a protected hydroxyl group, R2 is a hydrogen atom or R1 and R2, when taken together, mean a single linkage to from a double bond between the carbon atoms which they are linked, R3 is a hydroxyl group or a protected hydroxyl group, R4 is a hydrogen atom or a C1-C4 alkyl group, R5 is a hydrogen atom, a C1-C12 alkyl group, a C2-C12 alkenyl group, a C2-C12 alkynyl group, a C3-C10 cycloalkyl group, a C4-C10 cycloalkenyl group, a hydroxy C1-C12 alkyl group, a C3-C10 heterocyclic group, a phenyl group optionally substituted with a halogen atom; a hydroxyl group, a C1-C4 alkyl group, a trifluoromethyl group, or a C1-C4 alkyl group or a formula: A-B (A is a C1-C7 alkylene chain and B is a C3-C10 cycloalkyl group, a C4-C10 cycloalkenyl group, a C1-C12 alkoxy group, a C3-C10 cycloalkoxy group, a C4-C10 cycloalkenyloxy group, a C3-C10 heterocyclic group, or a phenyl or phenoxy group optionally (3) substituted with a halogen atom, a hydroxy group, a C1-C4 alkyl group, a trifluoromethyl group or a C1-C4 alkoxy group); or a non-toxic pharmaceutically acceptable salt thereof. Said compound have strong anti-ulcerous action or antithrombotic action, and are useful in treatment of ulcer or thrombosis.