Catalytic Asymmetric [2+3] Cyclizations of Azlactones with Azonaphthalenes

The first catalytic asymmetric [2+3] cyclization of azlactones with azonaphthalenes has been established. This strategy allowed the synthesis of a variety of chiral isatin derivatives in generally good yields and excellent enantioselectivities (up to 99 % yield, 98 % ee). The developed reaction has not only established a catalytic enantioselective [2+3] cyclization using azlactones as two‐carbon building blocks, but also enriches the chemistry of catalytic asymmetric cyclizations of azonaphthalenes. In addition, this protocol will provide a useful method for constructing enantioenriched 3,3′‐disubstituted isatin‐type frameworks. Dipol‐Ersatz: Die Titelreaktion wurde für Azlactone als C2‐Bausteine und Azonaphthaline als 1,3‐Dipol‐Surrogate entwickelt. Mit dieser Strategie gelang die Synthese vielfältiger chiraler Isatinderivate im Allgemeinen mit guten Ausbeuten und hervorragenden Enantioselektivitäten. CPA=chirale Phosphorsäure.