Regio- and stereoselective synthesis of Nor-nonactinic acid derivatives--kinetic reaction control in the Lewis acid mediated domino reaction of 1,3-dicarbonyl dianions with 1-bromo-2,3-epoxypropanes.

Reaction of 1,3-dicarbonyl dianions with epibromohydrin derivatives results in formation of functionalized 2-alkylidene-5-hydroxymethyltetrahydrofurans. These reactions proceed by chemoselective attack of the dianion onto the carbon attached to the bromine atom and subsequent nucleophilic attack of the resultant monoanion onto the epoxide. The cyclization products, which were formed with very good regio- and stereoselectivities, are of pharmacological relevance and represent versatile building blocks for the synthesis of natural products.