Electrooxidative C(sp3)-H Cyanation of Sparteine and Lupanine in Undivided Batch and Continuous-Flow Cells

ChemSusChem. 2024 Sep 21:e202401305. doi: 10.1002/cssc.202401305. Online ahead of print.

Abstract

Sparteine is widely used as a chiral ligand in asymmetric synthesis, but methods for providing efficient access to functionalized sparteine derivatives are still limited. Herein, we describe an electrochemical α-cyanation of sparteine-type bis-quinolizidine alkaloids. This method features commercially available setups for batch and single-pass continuous flow conditions, enabling easy gram scale synthesis of valuable racemic and enantiopure products. Moreover, insights into the selectivity of the reaction and overoxidation mechanisms are disclosed. This allows for the development of divergent oxidation pathways depending on the electrolysis conditions.

Keywords: Continuous Flow; Cyanation; Electrochemistry; Oxidation; Sparteine.