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

Abstract

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.

Recent Progress of Electron‐Withdrawing‐Group‐Tethered Arenes Involved Asymmetric Nucleophilic Aromatic Functionalizations

“…In 2018, Shi et al . reported a CPA‐catalyzed asymmetric [3+2] cycloaddition of the azonaphthanenes 81 with azlactones 113 , providing a wide range of chiral isatin derivatives 114 in good yields with high enantioselectivities [57] . As shown in Scheme 38, initiated by the Michael‐type reaction along with the expeditious rearomatization process, and followed by the intramolecular aminolysis, the cycloadduct was produced frequently (Scheme 38).…”