Diastereoselective Construction of Tetrahydro-Dispiro[indolinone-3,2′-pyran-5′,4″-pyrazolone] Scaffolds via an Oxa-Michael Cascade [4 + 2] Annulation Reaction

Abstract

A straightforward metal-free oxa-Michael cascade [4 + 2] annulation reaction was established between isatin-derived Morita−Baylis−Hillman (Is-MBH) alcohols with alkylidene pyrazolones to access structural diverse tetrahydro-dispiro[indolinone-3,2′-pyran-5′,4″-pyrazolone] scaffolds bearing two tertiary and two quaternary stereocenters. The Is-MBH alcohol was utilized as an oxa-Michael donor for the first time as a new approach in highly atom-economical transformations. This method offered a wide range of bioinspired novel tetrahydro-dispirooxindole-pyran-pyrazolone derivatives in excellent yields (up to 96%) and diastereoselectivities (up to >20:1) in a shorter reaction time (15 min).

Substrate-Controlled Diversity-Oriented Synthesis of Novel Polycyclic Frameworks via [4 + 2] and [3 + 2] Annulations of Ninhydrin-Derived MBH Adducts with 3,4-Dihydroisoquinolines

“…Therefore, it is still of great necessity and importance to develop ninhydrin-derived MBH adducts as substrates to access diverse functional cyclic compounds bearing indane-1,3-dione as promising pharmacophores. Notably, it still is highly desirable to find suitable reaction partners for MBH alcohols [66][67][68], further expanding the chemical space of MBH adducts.…”