Design and Synthesis of Rigid‐Featured Tertiary Amine‐Derived C2‐Symmetric Chiral Furan‐N,N′‐dioxide Ligands

Abstract

AbstractTo expand the chemical space of chiral N‐oxides and chiral furan‐containing ligands, herein we designed and synthesized a new class of rigid‐featured tertiary amine‐derived C2‐symmetric chiral furan‐N,N′‐dioxide (Fu‐2NO) ligands from optically pure l‐prolinamides/hydroxylprolinamides in operationally simple two steps and up to 57 % overall yield. The newly developed rigid‐featured chiral Fu‐2NO ligands possesses two pyrroloimidazolone‐based N‐oxides as non‐flat chiral walls, and afforded the opportunity for fine‐tuning the ligand electronic and conformational properties by judicious choice of the substituent in the nonligating nitrogen atom. More importantly, The Fu‐2NO ligands can tolerate air and moisture such that no special handling is needed for their storage, and can be applied in the Ni(II)‐catalyzed asymmetric Friedel‐Crafts alkylation reaction of indole.