New Chiral Diene Ligands for Rhodium-Catalyzed Conjugate Additions

Significance

Recently, Hayashi and others have introduced a new class of chiral bicyclic dienes which have been shown to be superior to bisphosphines as ligands in various transition-metal- ­catalyzed reactions. Unfortunately, the synthesis of many of these ligands is not trivial, limiting their broad applicability. In the present report, ­Okamoto, Hayashi and Rawal disclose a direct, two-step route to chiral diene L1 from commercially available (R)-(-)-α-phellandrene. Remarkably, in rhodium-catalyzed conjugate addition reactions L1 displayed higher levels of selectivity than several other well-known chiral dienes.