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.
The use of (R)-(−)-(DTBM-SEGPHOS)CuH effects a highly enantioselective 1,2-hydrosilylation of prochiral diaryl ketones to yield nonracemic diarylmethanols in excellent yields.
C.-T. Lee, B. H. Lipshutz, Org. Lett., 2008, 10, 4187-4190.
Asymmetric ligand-accelerated catalysis by copper hydride allows the synthesis of valued nonracemic allylic alcohols in very good yields.
R. Moser, Ž. V. Bošković, C. S. Crowe, B. H. Lipshutz, J. Am. Chem. Soc., 2010, 132, 7852-7853.
A direct asymmetric copper hydride (CuH)-catalyzed coupling of α,β-unsaturated carboxylic acids with aryl alkenes provides chiral α-aryl dialkyl ketones. The reaction tolerates various substrate substitution patterns, sensitive functional groups, and heterocycles.
Y. Zhou, J. S. Bandar, S. L. Buchwald, J. Am. Chem. Soc., 2017, 139, 8126-8129.
Judicious choice of ligand for both copper(I) hydride and palladium catalysis enabled a hydroarylation protocol to work for an extensive array of aryl bromides and styrenes, including β-substituted vinylarenes and six-membered heterocycles, under relatively mild conditions.
S. D. Friis, M. T. Pirnot, S. L. Buchwald, J. Am. Chem. Soc., 2016, 138, 8372-8375.
A ligand-modified, economical version of Stryker's reagent is based on a bidentate, achiral bis-phosphine. Generated in situ, “(BDP)CuH” smoothly effects conjugate reductions of a variety of unsaturated substrates, including those that are normally unreactive toward Stryker's reagent.
B. A. Baker, Ž. V. Bošković, B. H. Lipshutz, Org. Lett., 2008, 10, 289-292.
Taking advantage of micellar catalysis in water, asymmetric hydrosilylation reactions can be conducted at ambient temperatures using water as the global medium.
S. Huang, K. R. Voigtritter, H. B. Unger, B. H. Lipshutz, Synlett, 2010, 2041-2044.
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.
A copper hydride-catalyzed, enantioselective, intramolecular hydroalkylation of halide-tethered styrenes enables the synthesis of enantioenriched cyclobutanes, cyclopentanes, indanes, and six-membered N- and O-heterocycles.
Y.-M. Wang, N. C. Bruno, A. L. Placeres, S. Zhu, S. L. Buchwald, J. Am. Chem. Soc., 2015, 137, 10524-10527.
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.
Treatment of β,β-disubstituted-α,β-unsaturated ketones bearing a ketone residue with in situ generated, catalytic CuH ligated by a nonracemic ligand leads to cyclic aldol products with three newly created adjacent chiral centers. Excellent diastereoselectivities and enantioselectivities are obtained for several examples studied.
B. H. Lipshutz, B. Amorelli, J. B. Unger, J. Am. Chem. Soc., 2008, 130, 14378-14379.
The use of CuCl and NaBH4 enables an efficient, one-pot method for the highly chemoselective synthesis of δ-lactols from α,β-unsaturated δ-lactones in methanol.
Y. Matsumoto, M. Yonaga, Synlett, 2014, 25, 1764-1768.
The hydroallylation of terminal alkyl and aryl alkynes with simple allyl phosphates and 2-substituted allyl phosphates provides skipped dienes. The hydroallylation of functionalized internal alkynes enables the synthesis of complex trisubstituted alkenes.
M. Mailig, A. Hazra, M. K. Armstrong, G. Lalic, J. Am. Chem. Soc., 2017, 139, 6969-6977.
A copper hydride-catalyzed SN2′-reduction of propargylic carbonates provides functionalized allenes in good yields. The method takes advantage of the stabilizing effect of NHC ligands on CuH and offers high reactivity, stereoselectivity, and functional group tolerance.
C. Deutsch, B. H. Lipshutz, N. Krause, Org. Lett., 2009, 11, 5010-5012.
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. Int. Ed., 2004, 43, 2228-2230.
A CuH-catalyzed hydroamination of alkenes using an amine transfer reagent and a silane provides chiral amines with high efficiency and stereoselectivity. However, the current technology has been limited to dialkylamine transfer reagents (R2NOBz). A modified type of monoalkylamine transfer enabled the synthesis of chiral secondary amines, including those derived from amino acid esters, carbohydrates, and steroids.
D. Niu, S. L. Buchwald, J. Am. Chem. Soc., 2015, 137, 9716-9721.
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.
A range of 3-aryl-3-pyridylacrylonitriles were reduced with high levels of enantioselectivity under optimal conditions employing a copper/Josiphos complex in the presence of polymethylhydrosiloxane (PMHS).
D. Lee, Y. Yang, J. Yun, Org. Lett., 2007, 9, 2749-2751.
Cu-catalyzed asymmetric conjugate reduction of β-substituted ketones leads to enantiomerically enriched diphenylsilyl enol ethers, which are utilized in a diastereoselective Pd-catalyzed α-arylation of various aryl bromides to yield disubstituted cycloalkanones with excellent levels of enantiomeric and diastereomeric purity. The procedure can be carried out in one-pot.
J. Chae, J. Yun, S. L. Buchwald, Org. Lett., 2004, 6, 4809-4812.
A diastereo- and enantioselective CuH-catalyzed method for the preparation of highly functionalized indolines offers mild reaction conditions and high degree of functional group compatibility. This method is highly valuable for the synthesis various cis-2,3-disubstituted indolines in high yield and enantioselectivity.
E. Ascic, S. L. Buchwald, J. Am. Chem. Soc., 2015, 137, 4666-4669.