A new methodology of intramolecular hetero Diels-Alder reaction with β-alkoxy-substituted conjugated nitroalkenes as heterodienes: stereoselective one-pot synthesis of trans-fused bicyclic γ-lactones

摘要

Tandem reaction of (E)-1-ethoxy-2-nitroethylene with δ,ε-unsaturated alcohols leading to stereoselective trans-fused bicyclic γ-lactones has been developed using a catalytic amount of a Lewis acid such as Yb(OTf)_3 and Ni(ClO_4)_2·6H_2O. This process involves the stereoselective tandem transetherification-intramolecular hetero Diels-Alder reaction leading to bicyclic nitronates, and sequential transformation of the nitronate moiety to a lactone functional group under similar reaction conditions in good yields.