Metal-Free, Organocatalytic Asymmetric Transfer Hydrogenation of α,β-Unsaturated Aldehydes

Selective reduction without metals: An imidazolidinone salt effectively catalyzes the highly enantioselective biomimetic transfer hydrogenation of α,β‐unsaturated aldehydes to give the saturated analogues using a synthetic dihydropyridine cofactor (see scheme). Remarkably only one enantiomer forms regardless of the configuration of the enal starting material.