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DuPhos is a class of asymmetric ligands for asymmetric synthesis. The name DuPhos is derived from the chemical company that developed this type of ligand (DuP, DuPont) and the compound class of phospholanes (Phos) it belongs to. This diphosphine ligand type was introduced in 1991 by M.J. Burk 〔''C2-symmetric bis(phospholanes) and their use in highly enantioselective hydrogenation reactions'' Mark J. Burk J. Am. Chem. Soc., 1991, 113 (22), pp 8518–8519 〕〔''Preparation and use of C2-symmetric bis(phospholanes): production of .alpha.-amino acid derivatives via highly enantioselective hydrogenation reactions'' Mark J. Burk, John E. Feaster, William A. Nugent, Richard L. Harlow J. Am. Chem. Soc., 1993, 115 (22), pp 10125–10138 〕 and first demonstrated in asymmetric hydrogenation of certain enamide esters to amino acid precursors: : Other phosphine asymmetric ligands were known at the time (DIPAMP, BINOL, CHIRAPHOS) but the new ligand was found to be more effective. ==Description== The ligand consists of two 2,5-alkyl-substituted phospholane rings (the phosphorus analog of THF) connected via a 1,2-phenyl bridge. The alkyl group can be methyl, ethyl, propyl or isopropyl. In the closely related bis(dimethylphospholano)ethane or BPE ligand 〔''New electron-rich chiral phosphines for asymmetric catalysis'' Mark J. Burk, John E. Feaster, Richard L. Harlow Organometallics, 1990, 9 (10), pp 2653–2655 〕〔New chiral phospholanes; Synthesis, characterization, and use in asymmetric hydrogenation reactions Tetrahedron: Asymmetry, Volume 2, Issue 7, 1991, Pages 569-592 Mark J. Burk, John E. Feaster, Richard L. Harlow 〕 the phenyl bridge is replaced by an 1,2-ethyl bridge. Both compounds can be obtained from the corresponding chiral diol through conversion to the cyclic sulfate and reaction with lithiated phenylbisphosphine. In DuPhos the phosphorus atoms are electron-rich making the resulting metal complexes reactive. The phosphorus atoms also introduce a kind of pseudo-chirality making enantioselection independent of the overall chemical conformation 〔''Recent Developments in Catalytic Asymmetric Hydrogenation Employing P-Chirogenic Diphosphine Ligands'' Karen V. L. Crépy, Tsuneo Imamoto Advanced Synthesis & Catalysis Volume 345 Issue 1-2, Pages 79 - 101 2003 〕 Another early application is the synthesis of unnatural chiral amino acids in a formal reductive amination 〔''Enantioselective hydrogenation of the C:N group: a catalytic asymmetric reductive amination procedure'' Mark J. Burk, John E. Feaster J. Am. Chem. Soc., 1992, 114 (15), pp 6266–6267 〕 for example starting from benzophenone and the hydrazone of benzoyl chloride:〔''Catalytic asymmetric reductive amination of ketones via highly enantioselective hydrogenation of the C=N double bond'' Mark J. Burk , Jose P. Martinez, John E. Feaster and Nick Cosford Tetrahedron Volume 50, Issue 15, 11 April 1994, Pages 4399-4428 〕 : In the original scope the metal catalyst was rhodium but catalysis by ruthenium was introduced in 1995 〔''Practical asymmetric hydrogenation of β-keto esters at atmospheric pressure using chiral Ru (II) catalysts'' J. P. Genêt, V. Ratovelomanana-Vidal, M. C. Caño de Andrade, X. Pfister, P. Guerreiro and J. Y. Lenoir Tetrahedron Letters Volume 36, Issue 27, 3 July 1995, Pages 4801-4804 〕 with the hydrogenation of the ketone group in β-keto esters: : 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DuPhos」の詳細全文を読む スポンサード リンク
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