Structure of adducts of isoindolo[2,1-a]benzimidazole derivatives with maleimides

•New isoindolo[2,1-a]benzimidale derivatives were synthesized.•The reactions between new isoindoles and maleimides were carried out.•For azoloisoindoles were isolated two different types of rearrangement adducts.•Reaction route depends on substituents and reaction conditions.

The selectivity of formation and some mechanistic insights during the synthesis of substituted isoindolo[2,1-a]benzimidazoles are discussed. Furthermore, the reactions of the obtained products with maleimides were carried out. Two types rearrangement adducts together with intermediate Michael type adducts were isolated. The influence of the reaction conditions and reagents ratio is discussed. Specific spectral criteria for the identification of the Michael type adducts are indicated.