Synthesis of 3-Fluoro-3-aryl Oxindoles: Direct Eeaetioselective α Arylation of Amides

摘要

Monodentate N-heterocyclic carbene (NHC) ligands have become ubiquitous in organometallic chemistry and catalysis. Conversely, development of chiral monodentate NHC ligands that induce high selectivity in asymmetric metal catalysis is still at an early stage with relatively few reports detailing enantioselectivities of 90% ee and higher. The main difficulties in designing efficient ligands of this type reside in placing stereocontrol elements at positions near the metal center without affecting the overall reactivity of the catalysts. Scheme 1 shows some of the most promising liganddesigns to date and highlights the fact that the inherent flexibility of the N substituents has to be restricted to afford ligands that efficiently transfer their chiral information.