Chiral tertiary alcohols forged with copper

To make a tertiary alcohol from a ketone, chemists will often use an organometallic reagent to muscle its way onto the ketone’s carbonyl carbon. But there are limitations to which substrates you can use in this reaction, because the organometallics will react with substituents other than the target carbonyl. Also, to do the reaction asymmetrically, which is desirable to make drug candidates, for example, chemists often have to add stoichiometric amounts of chiral additives. Seeking a method that overcomes these burdens, a team led by MIT’s Stephen L. Buchwald and the University of Pittsburgh’s Peng Liu has developed an asymmetric tertiary alcohol synthesis that uses catalytic amounts of copper hydride and a chiral phospholane ligand to couple a polyunsaturated hydrocarbon, such as an ene-yne, and a ketone (Science 2016, DOI: 10.1126/science.aaf7720). The reaction (one example shown) tolerates a range of coupling partners and proceeds in high yield and with high enantioselectivity. In many instances, the chemists built complex molecules with two adjacent chiral centers. With further ligand optimization, the reaction will become “a powerful tool for the asymmetric addition of olefin-derived nucleophiles to carbonyls that will be of broad synthetic utility,” the researchers believe.