Studies on tandem transesterification and intramolecular cycloaddition of nitrones. 2. Sequential bicyclization of α,α-dialkoxycarbonylnitrones with allyl alcohols
s with 1.5 equiv. of allyl alcohols in the presence of 0.1 equiv. of titaniumtetrachloride and molecular sieves 4A causes tandem transesterification, E,Z-isomerization of the nitrone moieties, and intramolecular 1,3-dipolar cycloaddition to furnish bicyclic compound having ester group at the bridge head position. These reactions rarely give double transesterification product due to high reactivity