Organocatalytic Nonclassical Trienamine Activation in the Remote Alkylation of Furan Derivatives.

A new approach for the stereoselective remote alkylation of furan derivatives is reported. The reaction of 5-alkylfurfurals with nitroolefins as electrophilic counterparts occurs at their exocyclic ε-position and proceeds through the intermediacy of a nonclassical catalytic trienamine intermediate. The aminocatalyst bearing a H-bonding unit is used to control the stereochemical reaction outcome confirming the usefulness of such catalytic systems for the remote functionalizations of carbonyl compounds. Target products with two adjacent stereogenic centers are obtained in excellent yields and with good to moderate stereoselectivities.