Design and synthesis of new functionalized isoindigo and (3Z,3′Z)-3,3′-(ethane-1,2-diylidene)bis(indolin-2-one) derivatives

A library of N,N-substituted isoindigo derivatives were prepared by reaction of isoindigo with a variety of alkylating agents in the presence of MeONa under mild conditions in yields of 65–80%. A new, more efficient synthesis of (3Z,3′Z)-3,3′-(ethane-1,2-diylidene)bis(indolin-2-one) is described by reaction of oxindole with glyoxal at reflux in methanol—a small library of N,N′-substituted derivatives were also prepared in 60–70% yield. Graphical abstract: .