Deep Eutectic Solvent Promoted Regioselective Synthesis of Densely Functionalized Mono and Bisindolylalkenes from β‐Ketodithioesters

Abstract

The inherent ambident reactive sites (electrophilic and nucleophilic) of β-ketodithioesters (β-KDEs) have been realised by treating them with indoles and indole-3-carbaldehydes resulting with the formations of two different types of densely functionalized alkenes. Knoevenagel condensations of β-KDEs with indole aldehydes have been conducted smoothly using the eco-friendly deep eutectic solvent (DES) medium to yield monoindole substituted alkenes. On the other hand, C-3 alkylation of indoles with α-oxoketene S,S-acetal by conjugateaddition-substitution pathway resulted in the regioselective synthesis of bisindoloyl alkenes in DES medium.