Construction of 3,4‐Dihydrocoumarin Derivatives with Adjacent Quaternary and Tertiary Stereocenters: Organocatalytic Asymmetric Michael Addition of 2‐Oxochroman‐3‐carboxylate Esters to trans‐β‐Nitroolefins

An asymmetric Michael addition of 2‐oxochroman‐3‐carboxylate esters to trans‐β‐nitroolefins is described. This strategy can give direct access to dihydrocoumarin derivatives bearing adjacent quaternary and tertiary stereocenters with up to >99% yield, >20:1 dr, and >99% ee. The adduct was further transformed to a spiro‐dihydrocoumarin compound in three steps with good yield. magnified image