Gold catalyzed asymmetric synthesis of axially chiral indole-fused diazocines

Atropisomerism, also called axial chirality, is a particular kind of chirality in which the rotation of a σ bond is constrained because of the steric or electric effects of bulky substituents. The main difference between classical stereoisomers and atropisomers is that classical stereocenters are often stable and racemize via a bondbreaking, while racemization for axially chiral compounds is possible through an intramolecular dynamic process that simply involves bond rotation.1 This time-dependent chirality shows great potential for drug development and has been observed in natural products. In addition many chiral catalysts and ligands that are frequently used in asymmetric synthesis are axially chiral compounds. 2 Among these substrates, axially chiral indole derivatives have been recognized as an important class of five-membered heterobiaryls, because of their presence in some natural alkaloids, chiral phosphine ligands and bioactive molecules. 3 Taking into account these premises, this poster will deal with our recent developments in the gold catalyzed asymmetric synthesis of axially chiral indole-fused diazocines. In particular, optimization of catalytic conditions and preliminary substrate scope of the reaction will be presented together with a mechanistic proposal.