mass m z 362 344 318 313 245 179 164 147 131 129 105 further it is confirmed that the thus obtained compound is sole one due to tlc analysis by using a mixed solvent of ethyl acetate cyclohexane 1 2 which is an eluent capable of separating the e isomer and z isomer depending on the above literature in the literature tetrahedron vol 37 no 25 pp 4391 4399 1981 the above compound has been led to carbacycline at high yield in the method as described in reference example 30 the same procedures were carried out as in reference example 30 except that 3e 4 methoxycarbonylbutylidene 6 exo hydroxymethyl 7 endo 1 methyl 1 methoxyethyloxy bicyclo 3 3 0 octane 35 mg 0 10 mmol was employed as the starting material to obtain 3e 4 methoxycarbonylbutylidene 6 exo 3 oxo 1 trans octenyl 7 endo 1 methyl 1 methoxyethyloxy bicyclo 3 3 0 octane 35 mg yield 80 as substantially colorless oily products nmr u03b4 cdcl 3 6 75 m 1h 6 17 amp 6 12 2xd j 16 hz 1h 5 25 t j 7 hz 1h 3 90 m 1h 3 68 s 3h 3 20 s 3h 1 34 s 6h 0 90 t j.