Enantioselective Synthesis of Cyclohexenol Derivatives from γ-Aryl-Substituted Enals via an Organocatalyzed Three-Component Reaction.

A three-component reaction between γ-aryl-substituted α,β-unsaturated aldehydes and nitroalkenes was realized by using cinchona alkaloid-derived (thio)ureas and squaramides via the dienolate intermediates. This unprecedented 1,3- and 1,5-reactivity of dienolates of the γ-aryl-α,β-unsaturated aldehydes led to the formation of cyclohexenol derivatives with four contiguous stereogenic centers and a chiral substituent at C2 with good diastereoselectivities and high ee values. Such reactivities of the dienolates are totally different from those of the corresponding dienamine intermediates.