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history
Hydrogenation has a relatively long history in organic synthesis. At the end of the 19th century, P. Sabitier initiated the hydrogenation using fine metal particles in the heterogeneous catalytic system . In 1961, the hydrogenation of olefins were also achieved in the homogenous catalytic system using RuCl3 by B.R. James and co-workers However, any of the reactions could achieve a significant stereoselectivity until 1971 when H. B. Kagan introduced DIOP, a chiral diphosphane ligand. The DIOP-Rh complex was used for the asymmetric hydrogenation of dehydro amino acid and could achieve 72% ee.



In 1980, Noyori introduced a cationic BINAP-Rh catalyst for the asymmetric hydrogenation of olefin. The Rh catalyst could achieve high ee(>90%), but the reaction was relatively slow and only worked under specific conditions. The scope of the reaction was also limited to the stereoselective hydrogenation of α-(acylamino)-acrylic acid or esters to make amino acid derivatives. In 1986, Noyori and coworkers discovered the BINAP-Ru dicarboxylate catalyst. The scope of the asymmetric hydrogenation was not limited to the synthesis of amino acid derivatives anymore, but also the hydrogenation of α,β- and β,γ- unsaturated carboxylic acids and allyric/homoallyric alcohols with high ee around 90%.



In 1991, Noyori and coworkers also found that the BINAP-Ru dihalide can catalyze the asymmetric hydrogenation of various functionalized ketones. . While the BINAP-Ru dicarboxylate could only efficiently catalyze the hydrogenation of olefins, the BINAP-Ru dihalide could effectively catalyze both the hydrogenation of olefins and functionalized C=O bond.



Even though the BINAP-Ru dihalide catalyst functionalized ketone, the hydrogenation of simple ketone was remaind as problem to solve. Since 1953, H. C Brown and coworkers have succesfully achieved and developed the chemo-, and stereo-selective reduction of C=O bond. The chemoselectivity over C=C bond was achieved using NaBH4, the diastereoselectivity was achieved using Selectrides , and enantioselectivity was achieved using chiral stoichiometric reagents. . However, all three selectivities could not be achieved at the same time. In 1995, Noyori has discovered that the RuCl2(phosphane)2(diamine)2 complex can catalyze the hydrogenation of unfunctionalized ketones. This system also had chemoselectivity on C=O bond over the more reactive C=C bond. The diastereoselectivity and the enantioselectivity could be achieved as well.