On the Reactions of Furan‐2,3‐diones with Oxindole (=1,3‐Dihydro‐2H‐indol‐2‐one) and Lawesson Reagent. Synthesis of New 1,3‐Dihydro‐2H‐indol‐2‐ones,Bis‐furanones,and Bis‐pyrrolones

Lactone analogues of 3‐substituted oxindoles (=1,3‐dihydro‐2H‐indol‐2‐ones) and nonbenzoid oxa‐analogous isoindigoid or nonbenzoid isoindigoid dyes were prepared by the reactions of furan‐2,3‐diones with oxindole and Lawesson reagent (Schemes 1 and 3), respectively. So, new derivatives of 2‐oxobutanoic acid, bis‐furanone, and bis‐pyrrolone, which are potentially biologically active compounds, were synthesized for the first time.