Asymmetric dual catalysis via fragmentation of a single rhodium precursor complex

A strategy for dual transition metal catalysis and organocatalysis is reported via the in situ disintegration of a single rhodium complex. The hereby generated chiral Lewis acid and l-β-phenylalanine synergistically catalyze the Michael addition of α,α-disubstituted aldehydes to α,β-unsaturated 2-acyl imidazoles under the formation of vicinal quaternary/tertiary stereocenters. Conveniently, the chiral-at-metal rhodium catalyst can be synthesized in just two steps starting from rhodium trichloride without the need for any chromatography.