Organic & Biomolecular Chemistry Blog

Scientists from Japan report on the use of thionium activation for nucleophilic functionalization of indole derivatives at the 2-alpha position.

In this hot paper Kazuhiro Higuchi and Tomomi Kawasaki and coworkers at Meiji Pharmaceutical University expand on their communication from Chem. Comm. on the aliphatic C–H functionalization at the indole 2α-position mediated by acyloxythionium species generated from sulfoxides, including DMSO, and TFAA.

By using this method the indole ring is transformed into an allyl thionium species, and so is highly activated for nucleophilic attack from a wide variety of nucleophiles. Kawasaki make use of simple and readily available reagents, making the reaction a convenient route to functionalize alpha to the indole ring in a very straightforward fashion, enabling the introduction of O-, N- and C- substituents in a one-pot procedure.

For all the details read this paper for free today.

Sulfoxide-TFAA and nucleophile combination as new reagent for aliphatic C–H functionalization at indole 2α-position
Masanori Tayu, Kazuhiro Higuchi, Masato Inaba and Tomomi Kawasaki
DOI: 10.1039/C2OB26944A