Pd-Catalyzed Borylative Cyclization of 1,6-Enynes

Pd-catalyzed cyclization of 1,6-enynes in the presence of bis(pinacolato)diboron affords homoallylic alkylboronates. The reaction is general and proceeds with differently substituted alkenes and with both internal and terminal alkynes. It tolerates the presence of β-hydrogens and is stereoselective in the formation of both the new stereogenic centers and the alkene. This synthesis of alkylboronates avoids the use of highly nucleophilic reagents and is compatible with most functional groups.