{"product_id":"iridium-catalyzed-asymmetric-hydrogenation-of-furan-derivatives-and-thiophene-1-1-dioxides-von-larissa-pauli","title":"Iridium-Catalyzed Asymmetric Hydrogenation of Furan Derivatives and Thiophene 1,1-Dioxides","description":"\u003cp\u003eThe main focus of the research presented in this dissertation was to broaden the substrate scope of the iridium-catalyzed asymmetric hydrogenation of heterocyclic compounds. In view of the fact that a widely applicable hydrogenation system for the reduction of structurally diverse furans and benzofurans is to date not available, a thorough investigation of furan, benzofuran and thiophene 1,1-dioxide derivatives was carried out. Mono- and disubstituted furan derivatives were synthesized and submitted to iridium-catalyzed hydrogenation reactions. While 3-substituted furans were reduced using a catalyst based on a cyclopentane-annulated bicyclic pyridine-phosphine ligand with high enantiomeric excess (95¿99% ee) and conversion (83¿99%), 2-substituted counterparts proved to be less reactive (80¿97% conv., 65¿82% ee) with the same catalyst. Asymmetric hydrogenation of 2,4-disubstituted furans proved to be challenging for several reasons, not least because of the problem of controlling the cis\/trans selectivity. Surprisingly, in the iridium-catalyzed hydrogenation of 3-substituted benzofurans only one catalyst, based on the cyclohexane-annulated pyridine-phosphinite ligand, showed high activity and enantioselectivity (75¿89% conv., 91¿92% ee), whereas the five-membered ring analog suffered from moderate activity and enantioselectivity. In contrast, the 2-alkyl substituted benzofurans gave superior results (99% conv., 97¿99% ee). Disubstituted thiophene 1,1-dioxides were also investigated in the iridium-catalyzed asymmetric hydrogenation. The hydrogenation of 3,4 disubstituted thiophene 1,1 dioxides using a catalyst based on a cyclopentane-annulated bicyclic pyridine-phosphine ligand gave inferior results to those obtained with their 2,5 disubstituted counterparts.\u003c\/p\u003e\u003cdiv class=\"aw-variant-hidden-subtitle-div\" id=\"aw-variant-subtitle-9783954048519\"\u003e\u003ch3\u003e\u003c\/h3\u003e\u003c\/div\u003e","brand":"Libri","offers":[{"title":"Softcover - 9783954048519","offer_id":39463144849501,"sku":"9783954048519","price":33.2,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0940\/0622\/files\/19dbfcf0-0b5b-4bf4-a8ff-c8206bc3b673.jpg?v=1776495832","url":"https:\/\/shop.autorenwelt.de\/products\/iridium-catalyzed-asymmetric-hydrogenation-of-furan-derivatives-and-thiophene-1-1-dioxides-von-larissa-pauli","provider":"Autorenwelt Shop","version":"1.0","type":"link"}