1.
J Org Chem
; 84(11): 6679-6688, 2019 06 07.
Artículo
en Inglés
| MEDLINE
| ID: mdl-31083948
RESUMEN
An efficient strategy for stereo-controlled synthesis of potential biological and structurally complex chromanone-based spirocyclohexaneoxindoles via an organocatalytic domino formal double Michael cycloaddition of bifunctional chromone-oxindole synthons and nitroolefins is reported. These products possessing five adjacent stereocenters including one spiro quaternary carbon center, were smoothly afforded in up to 85% yield, >99% ee, and >20:1 dr. This strategy benefits from the intramolecular nature of the second Michael reaction step, through counterbalancing the lower electrophilicity of these unactivated chromones to facilitate the reaction.