Trialkylborane-Mediated Multicomponent Reaction for the Diastereoselective Synthesis of Anti-δ,δ-Disubstituted Homoallylic Alcohols.

The trialkylborane/O2-mediated reaction of propargyl acetates having a tributylstannyl group at an alkyne terminus with aldehydes in a THF-H2O solvent system gave anti-δ,δ-disubstituted homoallylic alcohols with good to high diastereoselectivity. Intriguingly, two alkyl groups derived from trialkylborane were embedded into the reaction product. The trialkylborane plays a key role not only as a radical initiator but also as a source of alkyl radicals.

Pd-Catalyzed Three-Component Reaction of 3-(Pinacolatoboryl)ally Acetates, Aldehydes, and Organoboranes: A New Entry to Stereoselective Synthesis of (Z)-anti-Homoallylic Alcohols.

The Pd-catalyzed three-component reaction of 3-(pinacolatoboryl)allyl acetates, aldehydes, and organoboranes is described. The reaction is initiated by the formation of an allylic gem-palladium/boryl intermediate, which then undergoes allylation of aldehydes by allylboronates followed by a coupling reaction of in situ generated (Z)-vinylpalladium acetates with organoboranes to provide the (Z)-anti-homoallylic alcohols with high levels of diastereoselectivity and alkene stereocontrol.