Synthesis and antiaggregation activity of prostacyclin analogs. II. Direct synthesis of 15-fluoro-13,14-didehydrocarbacyclin

E- and Z-isomers of 15-fluoro-13,14-dehydrocarbacyclin were synthesized starting from 2,3-epoxy-bicyclo3.3.0]octan-6-one ethylene ketal with the use of 3-fluoro-1-octynydlithium.BF3 reagent and Wittig condensation. The ratio of isomeric the oxirane opening reaction and Wittig olefinization products was in each case 1:1. The synthesized compounds were identified by 13C NMR spectra. The antiaggregating activity of 5E-isomer was 2 x 10(-4) of the activity of corresponding 15-hydroxy compound, 5Z-isomer being even less active.