{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T14:40:16Z","timestamp":1790260816117,"version":"4.1.0"},"reference-count":94,"publisher":"Wiley","issue":"22","license":[{"start":{"date-parts":[[2005,8,30]],"date-time":"2005-08-30T00:00:00Z","timestamp":1125360000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Chemistry A European J"],"published-print":{"date-parts":[[2005,11,4]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>A library of 19 chiral tropos phosphorus ligands, based on a flexible (tropos) biphenol unit and a chiral P\u2010bound alcohol (11 phosphites) or secondary amine (8 phosphoramidites), was synthesized. These ligands were screened, individually and as a combination of two, in the rhodium\u2010catalyzed asymmetric hydrogenation of dehydro\u2010\u03b1\u2010amino acids, dehydro\u2010\u03b2\u2010amino acids, enamides and dimethyl itaconate. <jats:italic>ee<\/jats:italic> values up to 98\u2009% were obtained for the dehydro\u2010\u03b1\u2010amino acids, by using the best combination of ligands, a phosphite [<jats:bold>4<\/jats:bold>\u2010P(O)<jats:sub>2<\/jats:sub>O] and a phosphoramidite [<jats:bold>13<\/jats:bold>\u2010P(O)<jats:sub>2<\/jats:sub>N]. Kinetic studies of the reactions with the single ligands and with the combination of phosphite [<jats:bold>4<\/jats:bold>\u2010P(O)<jats:sub>2<\/jats:sub>O] and phosphoramidite [<jats:bold>13<\/jats:bold>\u2010P(O)<jats:sub>2<\/jats:sub>N] have shown that the phosphite, despite being less enantioselective, promotes the hydrogenation of methyl 2\u2010acetamidoacrylate and methyl 2\u2010acetamidocinnamate faster than the mixture of the same phosphite with the phosphoramidite, while the phosphoramidite alone is much less active. In this way, the reaction was optimized by lowering the phosphite\/phosphoramidite ratio (the best ratio is 0.25 equiv phosphite\/1.75 equiv phosphoramidite) with a resulting improvement of the product enantiomeric excess. A simple mathematical model for a better understanding of the variation of the enantiomeric excess with the phosphite\/phosphoramidite ratio is also presented.<\/jats:p>","DOI":"10.1002\/chem.200500464","type":"journal-article","created":{"date-parts":[[2005,8,30]],"date-time":"2005-08-30T04:19:35Z","timestamp":1125375575000},"page":"6701-6717","source":"Crossref","is-referenced-by-count":85,"title":["Rh\u2010Catalyzed Asymmetric Hydrogenation of Prochiral Olefins with a Dynamic Library of Chiral TROPOS Phosphorus Ligands"],"prefix":"10.1002","volume":"11","author":[{"given":"Chiara","family":"Monti","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cesare","family":"Gennari","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Umberto","family":"Piarulli","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Johannes G.","family":"de Vries","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andr\u00e9 H. M.","family":"de Vries","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laurent","family":"Lefort","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2005,10,26]]},"reference":[{"key":"e_1_2_6_1_2","volume-title":"Comprehensive Asymmetric Catalysis,","author":"Brown J. 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This physical process then becomes the rate determining step."},{"key":"e_1_2_6_72_2","doi-asserted-by":"publisher","DOI":"10.1021\/jo9809332"},{"key":"e_1_2_6_73_2","unstructured":"The use of chiral monodentate phosphites containing the biphenol unit had recently been described by Xiao and Chen in the rhodium\u2010catalyzed hydrogenation of dimethyl itaconate with moderate enantiomeric excess (eemax. 75\u2009% with9\u2010P(O)2O at \u221215\u2009\u00b0C;eemax. 57\u2009% with9\u2010P(O)2O at 20\u2009\u00b0C).[29]The use of a limited number of combinations of different phosphites was also surveyed and the results were shown to be inferior to the corresponding homocombinations."},{"key":"e_1_2_6_74_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4039(01)01895-0"},{"key":"e_1_2_6_75_2","unstructured":"The diastereomers caused by the different conformations of the biphenol unit are not considered in this model."},{"key":"e_1_2_6_76_2","unstructured":"In principle theKvalue may be determined experimentally by31P NMR. However NMR experiments by using [Rh(cod)2BF4] and various phosphite and phosphoramidite ligands (e.g.4\u2010P(O)2O and13\u2010P(O)2N) were inconclusive."},{"key":"e_1_2_6_77_2","doi-asserted-by":"publisher","DOI":"10.1021\/jo00408a041"},{"key":"e_1_2_6_78_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0957-4166(01)00082-9"},{"key":"e_1_2_6_79_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.tetlet.2003.12.037"},{"key":"e_1_2_6_80_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0957-4166(00)00208-1"},{"key":"e_1_2_6_81_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0040-4020(98)00096-9"}],"container-title":["Chemistry \u2013 A European Journal"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Fchem.200500464","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/chem.200500464","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T22:18:33Z","timestamp":1760307513000},"score":1,"resource":{"primary":{"URL":"https:\/\/chemistry-europe.onlinelibrary.wiley.com\/doi\/10.1002\/chem.200500464"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2005,10,26]]},"references-count":94,"journal-issue":{"issue":"22","published-print":{"date-parts":[[2005,11,4]]}},"alternative-id":["10.1002\/chem.200500464"],"URL":"https:\/\/doi.org\/10.1002\/chem.200500464","archive":["Portico"],"relation":{},"ISSN":["0947-6539","1521-3765"],"issn-type":[{"value":"0947-6539","type":"print"},{"value":"1521-3765","type":"electronic"}],"subject":[],"published":{"date-parts":[[2005,10,26]]}}}