Electrochemical Synthesis of (Aza)indolines via Dehydrogenative [3+2] Annulation: Application to Total Synthesis of (±)‐Hinckdentine A.

Abstract: An electrochemical synthesis of functionalized (aza)indolines through dehydrogenative [3+2] annulation of arylamines with tethered alkenes has been developed. Previous reported syntheses through similar inter‐ and intramolecular annulation reactions required noble‐metal catalysts and are mostly limited to terminal alkenes or 1,3‐dienes. The electrosynthesis employs the easily available and inexpensive ferrocene as the molecular catalyst and is compatible with di‐, tri‐ and even tetrasubstituted alkenes to construct indolines as well as the more challenging azaindolines. Employing the newly developed electrosynthesis as a key step, the total synthesis of marine alkaloid (±)‐hinckdentine A has been achieved in 12 steps (longest linear sequence) from commercially available materials. [ABSTRACT FROM AUTHOR]