Stereo‐ and Regioselective Construction of Spirooxindoles Having Continuous Spiral Rings via Asymmetric [3+2] Cyclization of 3‐Isothiocyanato Oxindoles with Thioaurone Derivatives

Abstract

A highly efficient enantioselective [3+2] cyclization of 3‐isothiocyanato oxindoles with thioaurone derivatives was explored for the synthesis of spirooxindoles containing continuous spiral ring structures. Three continuous spiral ring structures and three consecutive chiral centers (including two spiro quaternary stereocenters) were conveniently constructed at a time. In addition, an uncommon sulfur‐containing spirocyclic ring was constructed at the same time. The reaction went smoothly whether the alkenyl moiety of thioaurone derivatives was at 2‐position (up to 99 % yield, up to 99 % ee, up to > 20:1 dr) or at 3‐position (up to 96 % yield, up to 95 % ee, up to 12:1 dr).

Expeditious entry into carbocyclic and heterocyclic spirooxindoles

“…Gui et al reported a cinchona alkaloid-derived organocatalyst-mediated preparation of spiroxindoles 184-185 containing three contiguous chiral centers under mild conditions. 80 A novel [3 + 2]-cyclization of 3-isothiocyanato oxindoles 5s and thioaurone derivatives 182-183 with an alkenyl group at the second and third positions and an uncommon sulfur atom proceeds with excellent yield and enantioselectivity (Scheme 107).…”

Asymmetric Formal [3+2] Cycloaddition Reactions of 3-Isothio­cyanato Oxindoles: an Update

“…In 2020, Wei and co-workers explored an efficient enantioselective formal [3+2] cycloaddition reaction between 3isothiocyanato oxindoles 1 and thioaurone derivatives (Scheme 9). 19 The reaction proceeded smoothly whether the alkenyl moiety of thioaurone derivatives was at 2-position 20 or at 3position 21 in the presence of squaramide 22 or quinine 12, affording the corresponding products 23 (Scheme 9a, up to 98 % yield, 99 % ee, and > 20:1 dr) and 24 (Scheme 9b, up to 96 % yield, 95 % ee, and 12:1 dr) with three consecutive stereocenters and three continuous spiral ring.…”

Acid‐Controlled Regional Diverse Synthesis of CF3‐Containing Ketoimines and Application in the Construction of Bispiro[oxindole‐pyrrolidine‐benzothiophenone]s

“…Meanwhile, only a few papers can be found that conducted both of them in the same research system. The initial research was explored by Shi's group who performed [3+2] cycloaddition reaction with 3‐isothiocyanato oxindoles and benzothiophenones derivatives [9] . The alkenyl moiety either at 3‐position or 2‐position reacted smoothly in the presence of cinchona alkaloid derived organocatalyst.…”