Studies on tandem transesterification and intramolecular cycloaddition of nitrones. 1. Sequential bicyclization of α-methoxycarbonylnitrones with allyl alcohols

Article abstract of DOI:10.1016/0040-4020(94)00874-T

Treatment of α-methoxycarbonylnitrones with 5 equiv. of allyl alcohols in the presence of 1 equiv. of titanium tetraisopropoxide causes tandem transesterification, E,Z-isomerization of the nitrone moieties, and intramolecular cycloaddition to afford bicyclized compounds in one step. To reduce amounts of allyl alcohol, combined use of a catalytic amount of titanium tetraisopropoxide and molecular sieves 4A was found to be a more improved catalytic system. It was also found that reactions of (Z)-allyl alcohols with α-methoxycarbonylnitrone are more facile than those of (E)-allyl alcohols. This aspect was extended to geometry differentiated cycloaddition.