Catalyst- and Substituent-Controlled Regio- and Stereoselective Synthesis of Indolyl Acrylates by Lewis-Acid-Catalyzed Direct Functionalization of 3-Formylindoles with Diazo Esters.

A facile and efficient In(OTf)3- and BF3·OEt2-catalyzed direct transformation of 3-formylindoles with diazo esters has been developed for synthesizing diverse and functionalized indolyl acrylates. This one-pot protocol furnishes various (Z)-α-hydroxy-β-indolyl acrylates, (E)-β-(2-alkoxy-2-oxoethoxy)-α-indolyl acrylates, and (Z)-3-hydroxy-2-indolyl acrylates by a catalyst- and substituent-controlled, regio- and stereoselective cascade reaction. The protocol has several advantages, including low loading of the catalyst, mild reaction conditions, broad scope, and high functional group tolerance. The synthesized compounds can be further converted into diversely functionalized materials.