Two Approaches in the Synthesis of Planar Chiral Azinylferrocenes

Two synthetic routes to the chiral azinylferrocenes (CAFs) <b>5</b> and <b>15</b>, key intermediates for the synthesis of new enantiomerically enriched <i>P</i>,<i>N</i>-ligands, have been compared. The first approach is based on the palladium-catalyzed cross-coupling reaction of halogenated azines with organozinc derivatives of ferrocenes (the Negishi reaction). The second approach exploits a new synthetic methodology, which provides a shorter pathway, through the direct C–H functionalization of aromatics by the C–C coupling of halogen-free (hetero)­arenes with lithium ferrocenes bearing stereogenic C and S atoms. The palladium complexes of <i>P</i>,<i>N</i>-ligands have been used as catalysts for the Tsuji–Trost reaction, which proceeds with high enantioselectivity to give allylic substitution products in good yields

Two Approaches in the Synthesis of Planar Chiral Azinylferrocenes

Two synthetic routes to the chiral azinylferrocenes (CAFs) <b>5</b> and <b>15</b>, key intermediates for the synthesis of new enantiomerically enriched <i>P</i>,<i>N</i>-ligands, have been compared. The first approach is based on the palladium-catalyzed cross-coupling reaction of halogenated azines with organozinc derivatives of ferrocenes (the Negishi reaction). The second approach exploits a new synthetic methodology, which provides a shorter pathway, through the direct C–H functionalization of aromatics by the C–C coupling of halogen-free (hetero)­arenes with lithium ferrocenes bearing stereogenic C and S atoms. The palladium complexes of <i>P</i>,<i>N</i>-ligands have been used as catalysts for the Tsuji–Trost reaction, which proceeds with high enantioselectivity to give allylic substitution products in good yields