Improved synthesis and expanded application of CuIPhEt, a C2-symmetric N-heterocyclic carbenoid

by Spahn, Elizabeth Suzanne; Albright, Abigail Lynn; Shevlin, Michael; Pfaltz, Andreas; Pauli, Larissa; Gawley, Robert E.

An asym. synthesis of CuIPhEt has been achieved in 5 steps and 65% yield. Libraries of rhodium and iridium catalysts were screened to produce the C2-sym. aniline precursor. A Rh-DuanPhos catalyst was employed to access this intermediate with 98.6% enantioselectivity. After completing a large scale synthesis of the chiral hydrosilylation catalyst, the scope of applicability of CuIPhEt was expanded upon beyond simple alkyl-alkyl and alkyl-aryl ketones.