Catalyst-Controlled Diastereoselectivity Switch in the Asymmetric [3 + 2] Annulation of Isatin-Derived MBH Carbonates and 5-Alkenylthiazol-4(5 H)-ones

Org Lett. 2021 Oct 1;23(19):7336-7341. doi: 10.1021/acs.orglett.1c02421. Epub 2021 Sep 15.

Abstract

Exploration of the diastereodivergent synthesis of spirocyclic oxindoles has been challenging. Herein we report asymmetric [3 + 2] annulations of isatin-derived Morita-Baylis-Hillman (MBH) carbonates and 5-alkenylthiazol-4(5H)-ones. Interestingly, two different chiral catalysts, amide-phosphine and 4-dimethylaminopyridine (DMAP)-thiourea, could lead to two kinds of diastereomeric dispiro oxindoles with three contiguous stereogenic centers. The hexafluoroisopropanol (HFIP) additive plays a vital role in accelerating the reaction and tuning the diastereoselectivity. Moreover, both annulation adducts could be further converted to structurally diverse spirooxindoles.

Publication types

  • Research Support, Non-U.S. Gov't