Copper hydride
Recent Literature
Optimizations to generate CuH in situ have led to an efficient and
inexpensive hydrosilylation method for dialkyl ketones.
B. H. Lipshutz, C. C. Caires, P. Kuipers, W. Chrisman, Org. Lett., 2003, 5, 3085-3088.
A complex of CuH and Takasago's nonracemic ligand, DTBM-SEGPHOS, is an
especially reactive reagent for asymmetric hydrosilylation of
heteroaromatic ketones under very mild conditions. PMHS serves as an
inexpensive source of hydride for the in situ generation of CuH.
B. H. Lipshutz, A. Lower, K. Noson, Org. Lett., 2002, 4, 4045-4048.
A complex of catalytic amounts of CuH with a nonracemic JOSIPHOS or SEGPHOS
ligand leads to exceedingly efficient and
highly enantioselective 1,4-reductions of α,β-disubstituted enoates and
lactones using PMHS as the stoichiometric reducing agent.
B. H. Lipshutz, J. M. Servesko, B. R. Taft, J. Am. Chem. Soc., 2004, 126, 8352-8353.
Catalytic amounts of copper hydride ligated by a nonracemic SEGPHOS
ligand leads in situ to an extremely reactive species capable of
effecting asymmetric hydrosilylations of conjugated cyclic enones with
very high enantioselectivity.
B. H. Lipshutz, J. M. Servesko, T. B. Petersen, P. P. Papa, A. A. Lover, Org. Lett., 2004, 6, 1273-1275.
A novel process for the efficient, enantioselective hydrosilylation of
ketimines based on catalytic amounts of copper hydride, (R)-DTBM-SEGPHOS,
and an inexpensive silane (tetramethyldisiloxane, TMDS) has been developed.
The resulting products are converted to their free-base form upon mild
hydrolysis.
B. H. Lipshutz, H. Shimizu, Angew. Chem., 2004, 116, 2278-2280.
A highly enantioselective reduction of α,β-unsaturated nitriles can be
conducted by using a Cu(OAc)2/josiphos complex as the catalyst under
hydrosilylation conditions. The reaction provides access to valuable
β-aryl-substituted chiral nitriles in good yields and with excellent
enantioselectivities.
D. Lee, D. Kim, S. Yun, Angew. Chem. Int. Ed., 2006,45, 2785-2787.
Cu-catalyzed asymmetric conjugate reduction of β-substituted ketones
leads to enantiomerically enriched β-substituted diphenylsilyl enol ethers,
which are utilized in the Pd-catalyzed arylation of various aryl bromides.
This simple route to α-arylated cycloalkanones with excellent levels of
enantiomeric and diastereomeric purity can be carried out in one-pot too.
J. Chae, J. Yun, S. L. Buchwald, Org. Lett., 2004, 6, 4809-4812.
