PMID: 11929258Apr 4, 2002Paper

The first complete identification of a diastereomeric catalyst-substrate (alkoxide) species in an enantioselective ketone hydrogenation. Mechanistic investigations

Journal of the American Chemical Society
Christopher J A Daley, Steven H Bergens

Abstract

The enantioselective hydrogenations of the dialkyl 3,3-dimethyloxaloacetate ketone substrates (2, 3, and 4; alkyl = Me, (i)Pr, and (t)Bu, respectively) were catalyzed by [Ru((R)-BINAP)(H)(MeCN)(n)(sol)(3-n)](BF(4)) (1, n = 0-3, sol = THF or MeOH, (R)-BINAP = (R)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) in up to 82% ee (R). Reaction of the active catalyst 1 with 1 equiv of substrate (2, 3, or 4) in THF or MeOH solution formed the diastereomeric catalyst-alkoxide complexes [Ru((R)-BINAP)(MeCN)(OCH(CO(2)R)-(C(CH(3))(2)CO(2)R))](BF(4)) (5/6 R = Me, 8/9 R = (i)Pr, and 10 R = (t)Bu, respectively) via hydride addition to the ketone carbonyl carbon and ruthenium addition to oxygen. The absolute configurations at the alkoxide groups ((R)- for the major diastereomers 5, 8, and 10) were determined via cleavage of the ruthenium-alkoxide bond with 1 equiv of HBF(4).OEt(2). The solution structures of the major diastereomer catalyst-alkoxide complexes (5, 8, and 10) were unambiguously determined by variable-temperature NMR spectroscopy. The major diastereomers (5, 8, and 10) had the same absolute configuration as the major product enantiomers from the catalytic hydrogenation of 2, 3, and 4 with 1 as catalyst. The ratio of major to minor a...Continue Reading

Citations

Apr 11, 2012·Journal of the American Chemical Society·Sherzod T Madrahimov, John F Hartwig
May 12, 2010·Dalton Transactions : an International Journal of Inorganic Chemistry·Haixia LiZhi-Xiang Wang
Mar 20, 2004·Proceedings of the National Academy of Sciences of the United States of America·Séverine JeulinPhilippe Dellis
Aug 2, 2003·Biotechnology Progress·Hiroyuki Nagaoka
Apr 19, 2007·Chemistry, an Asian Journal·Yusuke ShimadaYoshiaki Nishibayashi
Jun 21, 2007·Chemistry : a European Journal·Walter BarattaPierluigi Rigo
Oct 24, 2008·Chemistry : a European Journal·Agnieszka BartoszewiczBelén Martín-Matute
Mar 3, 2012·Dalton Transactions : an International Journal of Inorganic Chemistry·Lili ZhaoZhi-Xiang Wang
Jul 27, 2011·Journal of the American Chemical Society·Frank M A GeilenWalter Leitner

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