Chiral Phosphine–Phosphite Ligands in Asymmetric Gold Catalysis: Highly Enantioselective Synthesis of Furo[3,4‐ d ]‐Tetrahydropyridazine Derivatives through [3+3]‐Cycloaddition

The Au I ‐catalyzed reaction of 2‐(1‐alkynyl)‐2‐alken‐1‐ones with azomethine imines regio‐ and diastereoselectively affords furo[3,4‐d]tetrahydropyridazines in a tandem cyclization/intermolecular [3+3]‐cycloaddition process under mild conditions. By employing a chiral gold catalyst (prepared in situ from a Taddol‐derived phosphine‐phosphite ligand, Me 2 SAuCl, and AgOTf) high yields and enantioselectivities (up to 94 % yield, up to 96 %  ee ) are obtained. The method provides an efficient modular route to substituted heterotricyclic furan derivatives and can be easily scaled up (using catalyst loads of only 0.15 mol %).