A Simple Protocol To Access Oxindole Derivatives Catalyzed By DMAP And Synthesis Of Multisubstituted Furans In Water

Oxindoles derivatives and multisubstituted furans are structural units of some drug molecules,this drug molecules can be shown in biological activity and pharmaceutical activity.Organic-catalyzed reactions and organic reactions in water under catalyst-free conditions have received more attention from chemists due to having mild conditions,efficiency,greenness,and ease of handling.This paper mainly introduces two annulations:one is DMAP-catalyzed[3+2]cycloaddition of isatin-derived Morita-Baylis-Hillman adducts with azo esters for synthesis of3-spiropyrazole-2-oxindolesand;another is direct synthesis of multisubstituted furans from enynones with sulfinic acids in water under catalyst-and additive free conditions.Details as follows:1.An efficient and regioselective DMAP catalyzed[3+2]cycloaddition of isatin-derived Morita-Baylis-Hillman adducts with azo esters was developed for the construction of 3-spiropyrazole-2-oxindoles.This protocol generated the desired spiropyrazoles in good to excellent yields with good functional group compatibility under mild reaction conditions.2.A facile and efficient tandem reaction of enynones with arylsulfinic acids was developed.A variety of multisubstituted furans were obtained in satisfactory yields via an O₂-oxidative single-electron-transfer process without any catalyst and additive in water.This tandem reaction tolerated a broad range of functional groups and very green.