Cyano(dialkylamino)boryl ethers of homopropargylic alcohols undergo intramolecular addition of a B-CN bond across their carbon-carbon triple bonds (cyanoboration) in the presence of palladium and nickel catalysts, furnishing five-membered cyclic boryl ethers regioselectively in good yields via 5-exo cyclization. The products were transformed into highly substituted alpha,beta-unsaturated nitriles via Suzuki-Miyaura coupling to aryl iodides, rhodium-catalyzed conjugative addition to methyl vinyl ketone, and rhodiumcatalyzed protodeborylation. (c) 2005 Elsevier B.V. All rights reserved.