Structure Identification of Precatalytic Phosphoramidite Complexes in Solution

Abstract

1+1 is more than 2: A binuclear copper phosphoramidite precatalyst with mixed trigonal/tetrahedral coordination environments (see picture) is proposed based on NMR spectroscopy, mass spectrometry, and elemental analysis. The precatalyst represents a new structural motif for stereoselective copper catalysts and explains ligand acceleration and salt sensitivity in highly enantioselective 1,4-additions to enones.