Copper-catalyzed functionalization of terminal or 1,1-disubstituted alkenes with bis(pinacolato)diboron and methanol provides formal hydroboration products with exceptional regiocontrol favoring the branched isomer. Through pairing this procedure with photocatalytic cross couplings using iridium and nickel co-catalysis, an effective, highly regiose-lective procedure for the hydroarylation of terminal alkenes is provided.

We have developed a bromination/alkynylation sequence that enables efficient transformation of simple cyclic enol ethers to difunctionalized products. The success of this strategy relies on a highly diastereselective, zinc-catalyzed addition of terminal alkynes to α-bromo oxocarbenium ions, formed in situ via ionization of acetal precursors. Using this method, trans-α-alkynyl-β-halo pyran and furan derivatives can be prepared with high diastereoselectivity and excellent functional group tolerance.

Diastereoselective, Zinc-Catalyzed Alkynylation of -Bromo Oxocarbenium Ions. -The bromination of dihydropyran (I) in AcOH followed by a Zn-catalyzed alkynylation of resulting acetal (III) leads to trans--alkynyl--bromo tetrahydropyrans (V), which can be converted into derivatives (VI), (VII), and (IX). The alkynylation of substrates (XI) and (XIV) proceeds analogously. -(HAIDZINSKAYA, T.; KERCHNER, H. A.; LIU, J.; WATSON*, M. P.; Org. Lett. 17 (2015) 15, 3857-3859, http://dx.