Lithium Binaphtholate-Catalyzed Enantioselective Enyne Addition to Ketones: Access to Enynylated Tertiary Alcohols

A new
catalytic enantioselective enyne addition to ketones has
been developed. In the presence of chiral lithium binaphtholate, the
addition reaction proceeded smoothly to produce a series of enynylated
tertiary alcohols in up to 96% yield and 94% enantiomeric excess.
Convenient transformation of the adduct via Pauson–Khand cycloaddition
reaction afforded the bicyclic product without detectable loss of
enantioselectivity. Furthermore, catalytic asymmetric enyne addition
to trifluoromethylketone was applied in the synthesis of the Efavirenz
analogue.