A mixture of 2-(
di-
tert-butylphosphino)biphenyl an
d dicarbonylacetonato rho
dium(I) provi
des an effectivecatalyst system for the a
ddition of alkynes to al
dehy
des an
d activate
d ketones. In contrast to the morecommon zinc-catalyze
d processes, enolizable 1,2-
dicarbonyls are excellent substrates for these rho
dium-catalyze
d a
dditions. This reaction allows for the formation of propargylic alcohols un
der mil
d con
ditions,tolerating many functional groups (such as carboxylic aci
ds) that are incompatible with other metho
ds.Little selectivity was observe
d in cases of unsymmetrical 1,2-
diketones. A
ddition of alkynes to al
dehy
deswith an a
djacent chirality center usually provi
des the Felkin a
ddition pro
duct with excellent selectivityin some cases. Stu
dies on the catalyst structure show that both the -
diketonate an
d a carbon monoxi
deligan
d appear to be boun
d to the active catalyst. The use of chiral phosphines to in
duce asymmetry in thepropargyl alcohol pro
ducts provi
de
d low enantioselectivity, which may be
due to the phosphine havinga
distal relationship to the reacting centers. Mo
dification of other ligan
ds, such as the -
diketonate, appearsto be a more promising avenue for the
development of an enantioselective variant.