The organobase-mediated diastereoselective spirocyclopropanation of barbiturate-based
olefins with 2,4-disubstituted benzyl chlorides has been developed. The reactions
were carried out efficiently to afford the desired spirobarbiturate-cyclopropanes
in up to 95% yield with more than 20:1 dr in favor of anti-isomers. In order to extend synthetic utility of the spiro-products, a Lewis acid
induced cyclopropane-ring-expansion isomerization was also demonstrated.
Key words
spirobarbiturate-cyclopropane - spirocyclopropanation - barbiturate-based olefin -
benzyl chloride - diastereoselective - synthetic methodology - organobase