A cobalt-catalyzed cross-coupling betweenalkyl iodides and cyclopropyl, cyclobutyl, and alkenyl Grignard reagents is disclosed. The reaction allows the introduction of strained rings on a large panel of primary and secondary alkyl iodides. The catalytic system is simple and nonexpensive, and the reaction is general, chemoselective, and diastereoconvergent. The alkene resulting from the cross-coupling
The 15-substituted-.omega.-pentanorprostaglandins and various intermediates employed in their preparation. The novel prostaglandins of this invention have been found to have activity profiles comparable to the parent prostaglandins, but exhibit a greater tissue specificity of action.