I. Perez et al., Atom-efficient metal-catalyzed cross-coupling reaction of indium organometallics with organic electrophiles, J AM CHEM S, 123(18), 2001, pp. 4155-4160
The novel metal-catalyzed cross-coupling reaction of indium organometallics
with organic electrophiles is described. Triorganoindium compounds (R3In)
containing alkyl, vinyl, aryl, and alkynyl groups are efficiently prepared
from the corresponding Lithium or magnesium organometallics by reaction wit
h indium trichloride. The cross-coupling reaction of R3In with aryl halides
and pseudohalides (iodide 2, bromide 5; and triflate 4), vinyl triflates,
benzyl bromides, and acid chlorides proceeds under palladium catalysis in e
xcellent yields and with high chemoselectivity. Indium organometallics also
react with aryl chlorides as under nickel catalysis. In the cross-coupling
reaction the triorganoindium compounds transfer; in a clear example of ato
m economy, all three of the organic groups attached to the metal, as shown
by the necessity of using only 34 mol % of indium. The feasibility of using
R3In in reactions with different electrophiles, along with the high yields
and chemoselectivities obtained, reveals indium organometallics to be usef
ul alternatives to other organometallics in cross-coupling reactions.