{"id":2940,"date":"2022-08-12T10:47:00","date_gmt":"2022-08-12T08:47:00","guid":{"rendered":"https:\/\/site.uit.no\/nordco2\/?p=2940"},"modified":"2024-10-11T12:20:38","modified_gmt":"2024-10-11T10:20:38","slug":"research-article-uit-4","status":"publish","type":"post","link":"https:\/\/site.uit.no\/nordco2\/2022\/08\/12\/research-article-uit-4\/","title":{"rendered":"Research Article: UiT"},"content":{"rendered":"\n<figure class=\"wp-block-image size-full\"><img fetchpriority=\"high\" decoding=\"async\" width=\"972\" height=\"526\" src=\"https:\/\/site.uit.no\/nordco2\/wp-content\/uploads\/sites\/344\/2024\/01\/images_large_ja2c06454_0016.jpeg\" alt=\"graphical abstract\" class=\"wp-image-2941\" srcset=\"https:\/\/site.uit.no\/nordco2\/wp-content\/uploads\/sites\/344\/2024\/01\/images_large_ja2c06454_0016.jpeg 972w, https:\/\/site.uit.no\/nordco2\/wp-content\/uploads\/sites\/344\/2024\/01\/images_large_ja2c06454_0016-300x162.jpeg 300w, https:\/\/site.uit.no\/nordco2\/wp-content\/uploads\/sites\/344\/2024\/01\/images_large_ja2c06454_0016-768x416.jpeg 768w, https:\/\/site.uit.no\/nordco2\/wp-content\/uploads\/sites\/344\/2024\/01\/images_large_ja2c06454_0016-693x375.jpeg 693w\" sizes=\"(max-width: 972px) 100vw, 972px\" \/><\/figure>\n\n\n\n<p>Title:<br><a href=\"https:\/\/pubs.acs.org\/doi\/10.1021\/jacs.2c06454\" data-type=\"URL\" data-id=\"https:\/\/pubs.acs.org\/doi\/10.1021\/jacs.2c06454\">Mechanistic Investigations of the Asymmetric Hydrogenation of Enamides with Neutral Bis(phosphine) Cobalt Precatalysts<\/a><\/p>\n\n\n\n<p>Abstract:<br>The mechanism of the asymmetric hydrogenation of prochiral enamides by well-defined, neutral bis(phosphine) cobalt(0) and cobalt(II) precatalysts has been explored using(<em>R<\/em>,<em>R<\/em>)-<sup>iPr<\/sup>DuPhos ((<em>R<\/em>,<em>R<\/em>)-<sup>iPr<\/sup>DuPhos = (+)-1,2-bis[(2<em>R<\/em>,5<em>R<\/em>)-2,5-diisopropylphospholano]benzene) as a representative chiral bis(phosphine) ligand. A series of (<em>R<\/em>,<em>R<\/em>)-(<sup>iPr<\/sup>DuPhos)Co(enamide) (enamide = methyl-2-acetamidoacrylate (MAA), methyl(<em>Z<\/em>)-\u03b1-acetamidocinnamate (MAC), and methyl(<em>Z<\/em>)-acetamido(4-fluorophenyl)acrylate (<sup>4F<\/sup>MAC)) complexes (<strong>1-MAA<\/strong>,\u00a0<strong>1-MAC<\/strong>, and\u00a0<strong>1-<\/strong><sup><strong>4F<\/strong><\/sup><strong>MAC<\/strong>), as well as a dinuclear cobalt tetrahydride, [(<em>R<\/em>,<em>R<\/em>)-(<sup>iPr<\/sup>DuPhos)Co]<sub>2<\/sub>(\u03bc<sub>2<\/sub>-H)<sub>3<\/sub>(H) (<strong>2<\/strong>), were independently synthesized, characterized, and evaluated in both stoichiometric and catalytic hydrogenation reactions. Characterization of (<em>R<\/em>,<em>R<\/em>)-(<sup>iPr<\/sup>DuPhos)Co(enamide) complexes by X-ray diffraction established the formation of the pro-(<em>R<\/em>) diastereomers in contrast to the (<em>S<\/em>)-alkane products obtained from the catalytic reaction. In situ monitoring of the cobalt-catalyzed hydrogenation reactions by UV\u2013visible and freeze-quench electron paramagnetic resonance spectroscopies revealed (<em>R<\/em>,<em>R<\/em>)-(<sup>iPr<\/sup>DuPhos)Co(enamide) complexes as the catalyst resting state for all the three enamides studied. Variable time normalization analysis kinetic studies of the cobalt-catalyzed hydrogenation reactions in methanol established a rate law that is first order in (<em>R<\/em>,<em>R<\/em>)-(<sup>iPr<\/sup>DuPhos)Co(enamide) and H<sub>2<\/sub>\u00a0but independent of the enamide concentration. Deuterium-labeling studies, including measurement of an H<sub>2<\/sub>\/D<sub>2<\/sub>\u00a0kinetic isotope effect and catalytic hydrogenations with HD, established an irreversible H<sub>2<\/sub>\u00a0addition step to the bound enamide. Density functional theory calculations support that this step is both rate and selectivity determining. Calculations, as well as HD-labeling studies, provide evidence for two-electron redox cycling involving cobalt(0) and cobalt(II) intermediates during the catalytic cycle. Taken together, these experiments support an unsaturated pathway for the [(<em>R<\/em>,<em>R<\/em>)-(<sup>iPr<\/sup>DuPhos)Co]-catalyzed hydrogenation of prochiral enamides.<\/p>\n\n\n\n<p>Find a list of publications by\u00a0NordCO<sub>2<\/sub>\u00a0members on our\u00a0<a href=\"https:\/\/site.uit.no\/nordco2\/publications\/\">Publications<\/a>\u00a0page\u00a0\ud83d\ude42<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Title:Mechanistic Investigations of the Asymmetric Hydrogenation of Enamides with Neutral Bis(phosphine) Cobalt Precatalysts Abstract:The mechanism of the asymmetric hydrogenation of prochiral enamides by well-defined, neutral &hellip;<\/p>\n","protected":false},"author":514,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"image","meta":{"ngg_post_thumbnail":0,"footnotes":""},"categories":[8],"tags":[],"class_list":["post-2940","post","type-post","status-publish","format-image","hentry","category-research","post_format-post-format-image"],"_links":{"self":[{"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/posts\/2940","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/users\/514"}],"replies":[{"embeddable":true,"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/comments?post=2940"}],"version-history":[{"count":1,"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/posts\/2940\/revisions"}],"predecessor-version":[{"id":2942,"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/posts\/2940\/revisions\/2942"}],"wp:attachment":[{"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/media?parent=2940"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/categories?post=2940"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/site.uit.no\/nordco2\/wp-json\/wp\/v2\/tags?post=2940"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}