Pd-catalyzed borylative polycyclization of enediynes to allylboronates

Pd-catalyzed dicyclization of 6-ene-1,11-diynes with bis(pinacolato)diboron affords synthetically useful allylboronates under smooth conditions. Two new C-C and one C-B bonds are stereospecifically formed in a single operation. The stereochemical outcome depends on the starting alkene configuration. The reaction is general and has been applied to differently substituted enediynes. Isolation of intermediate 1,3-dienes suggests a regioselective beta-hydrogen elimination along the reaction pathway.