Lewis‐Base‐Catalyzed Domino Reaction of Morita–Baylis–Hillman Carbonates of Isatins with Enolizable Cyclic Carbonyl Compounds: Stereoselective Access to Spirooxindole‐Pyrans

다국어 초록 (Multilingual Abstract)

The present paper reports an efficient, organocatalytic, environmentally friendly and stereoselective [3+3] one‐pot allylic alkylation/oxa‐Michael reaction by involving a wide range of Morita–Baylis–Hillman (MBH) carbonates of isatins and several pharmacologically attractive enolizable C−H activated cyclic carbonyl compounds such as 1,3‐binucleophiles, namely pyrazolones, isoxazolones, 4‐hydroxyxoumarins, 4‐hydroxy‐6‐methyl‐α‐pyrone, lawsone and dimedone in a biomass‐derived 2‐MeTHF as green solvent catalyzed by DABCO as a solid Lewis‐base catalyst. This protocol delivers a unique class of medicinally promising spirooxindole‐fused‐dihydropyran scaffolds.
In‐spire‐ing: A stereoselective spiroannulation reaction of Morita–Baylis–Hillman (MBH) carbonates of isatins with a variety of biologically exciting enolizable cyclic carbonyl compounds in 2‐MeTHF as a green solvent has been developed to afford a diverse set of dihydrospiro[indoline‐3,4′‐pyran]‐2‐one scaffolds bearing an all‐carbon spiro center in good to high yields with excellent diastereoselectivities (up to 99:1 d.r.).