Site-Selective (Z)-α-Borylalkenyl Copper Systems for Nucleophilic Stereodefined Allylic Coupling.

1,1-Diborylalkenes can be transformed into (Z)-skipped dienes through Cu I -phosphine catalyzed allylic coupling reactions. The energetically preferred formation of (Z)-α-borylalkenyl copper (I) species and the subsequent nucleophilic attack, explains the stereoselective nucleophilic substitution with allyl bromides. The eventual treatment of (Z)-skipped dienes with NaO t Bu promotes cyclization/aromatization patterns via enyne intermediates.