Asymmetric Synthesis of Functionalized Tricyclic Chromanes via an Organocatalytic Triple Domino Reaction.

A highly stereoselective triple domino reaction for the synthesis of functionalized tricyclic chromane scaffolds has been developed. A secondary amine-catalyzed domino Michael/Michael/aldol condensation reaction between aliphatic aldehydes, nitro-chromenes, and α,β-unsaturated aldehydes leads to the formation of synthetically important tricyclic chromanes bearing four contiguous stereogenic centers including a tetrasubstituted carbon in good yields (20-66%) and excellent stereoselectivities (>20:1 dr and >99% ee).