Iron-catalyzed stereoselective C–H alkylation for simultaneous construction of C–N axial and C-central chirality
Zijing Zhang, Nicolas Jacob, Shilpa Bhatia, Philipp Boos, Xinran Chen, Joshua C. DeMuth, Antonis M. Messinis, Becky Bongsuiru Jei, João C. A. Oliveira, Aleksa Radović, Michael L. Neidig, Joanna Wencel‐Delord, Lutz Ackermann
Abstract
The assembly of chiral molecules with multiple stereogenic elements is challenging, and, despite of indisputable advances, largely limited to toxic, cost-intensive and precious metal catalysts. In sharp contrast, we herein disclose a versatile C-H alkylation using a non-toxic, low-cost iron catalyst for the synthesis of substituted indoles with two chiral elements. The key for achieving excellent diastereo- and enantioselectivity was substitution on a chiral N-heterocyclic carbene ligand providing steric hindrance and extra represented by noncovalent interaction for the concomitant generation of C-N axial chirality and C-stereogenic center. Experimental and computational mechanistic studies have unraveled the origin of the catalytic efficacy and stereoselectivity.