A chemo- and regioselective C6-functionalization of 2,3-disubstituted indoles: highly efficient synthesis of diarylindol-6-ylmethanes

An organocatalytic chemo- and regioselective C6-functionalization of 2,3-disubstituted indoles has been established via a reaction with ortho-hydroxybenzyl alcohols, which afforded biologically important diarylindol-6-ylmethanes in overall high yields (up to 99% yield). This protocol not only provides an efficient method for constructing biologically important diarylindol-6-ylmethane frameworks in an atom economical fashion, but also serves as a good example for the direct catalytic C6-functionalization of indoles, which have been rarely investigated. More importantly, the preliminary biological evaluation revealed that this new class of diarylindol-6-ylmethanes exhibited strong cytotoxicity to HeLa cell lines.