C3-Functionalization of indoles with α-heteroaryl-substituted methyl alcohols

Abstract

The transition metal-free Cs₂CO₃/Oxone®-mediated C3-alkylation of indoles proceeds in moderate to high yields with a variety of C4–C7 functionalized indoles and is applicable to 2-, 3- and 4-hydroxymethyl pyridines and related electron-deficient heterocycles, permitting novel late-stage drug functionalizations. Preliminary mechanistic studies support a hydrogen autotransfer-type chain process starting with an initial oxidation of the alcohol to the corresponding aldehyde, followed by a subsequent condensation onto indole and reduction/hydride delivery from another equivalent of the primary alcohol.