Enantioselective Steglich Rearrangement with a Highly Active Chiral Nucleophilic Catalyst

Mandai and Suga et al. have reported an enantioselective Steglich rearrangement (an intramolecular acylation rearrangement) using a new chiral nucleophilic catalyst.¹⁾ 4-Dimethylaminopyridine (DMAP) has long been recognized as an effective nucleophilic catalyst. In this report, they show that the design and synthesis of a new asymmetric organocatalyst consisted of 1,1-binaphthyl and DMAP moieties which can be used as an effective catalyst for Steglich rearrangement of derivatives possessing a phenyl carbonate group. The rearrangement of the phenoxy carbonyl group sufficiently proceeds using as little as 0.5 mol% of the catalyst and produces optically active oxindole derivatives in high yield with up to a 98:2 enantiomeric ratio. Additionally, this catalyst is effective in the kinetic resolution of a racemic secondary carbinol through enantioselective acylation (selectivity factor up to 80).^1,2) Furthermore, this catalyst can be recovered by column chromatography elution in 95% yield, and used in the same reaction.