Privileged Ligands Research Articles

Recent Advances in Metal-Catalyzed Asymmetric Conjugate Additions

The conjugate addition of carbon nucleophiles to acceptor activated olefins is one of the most important reactions for carbon-carbon bond formation. With optically active metal complexes this transformation can be catalyzed enantioselectively. This review is a collection of the newer literature (since 2001) on this topic. The metal salts and complexes applied are in a broad range, starting from solely Lewis acidic M(II) and M(III) compounds, such as magnesium, zinc, boron, aluminum and the lanthanoids. Transition-metal catalysts suitable for asymmetric conjugate additions are compounds of ruthenium, iridium, nickel, and palladium. The most flourishing fields are, however, the catalysis with rhodium and copper complexes. Rhodium catalysts often have a chiral diphosphane like BINAP, or an optically active olefin as the ligand, the latter being a newer development. The privileged ligand structures for copper catalysts are monodentate phosphoramidites with axially chiral BINOL or other biphenol units.

Synthesis of 2,3,4,7-tetrahydro-1 H-azepines as privileged ligand scaffolds for the design of aspartic protease inhibitors via a ring-closing metathesis approach

We have developed a short and highly efficient synthetic strategy towards the hitherto hardly known 3,5- and 3,6-disubstituted 2,3,4,7-tetrahydro-1 H-azepine scaffold via a ring-closing metathesis approach utilizing inexpensive and readily available starting material such as methyl acrylate and allylamine. Both seven-membered azacycle scaffolds bearing suitable functional groups, which can easily be modified by means of standard synthetic chemistry, serve as non-peptidic heterocyclic core structures for the further design and synthesis of aspartic protease inhibitors. Through specific decoration with appropriate side chains, individual inhibitors can be tailored with respect to selectivity towards particular family members. A first generation of this class of non-peptidic inhibitors have been tested against the aspartic proteases Plasmepsin II and HIV-I protease, respectively, showing promising activity as well as selectivity with IC 50 values in the micromolar range.

Solvias Josiphos Ligands: From Discovery to Technical Applications

The various stages from the invention of a ligand class to its technical application are described and illustrated by the case history of the Solvias Josiphos ligands. First, the prerequisites for a so-called “privileged ligand” are discussed, followed by a description of the Josiphos ligand family and their technical synthesis. Then, the catalytic performance of various Josiphos metal complexes in model reactions and in “real world” synthetic applications are summarized in the next two chapters. In the last part, three technical processes using Josiphos ligands are described: (i) The Ir-PPF-P(Xyl)2-catalyzed hydrogenation of MEA imine for the large scale production of the herbicide (S)-metolachlor; (ii) the application of a Rh-PPF-P(tBu)2 complex for the hydrogenation of a biotin intermediate; (iii) the Ru-PPF-P(Cy)2-catalyzed hydrogenation of a tetrasubstituted C=C bond for the production of cis-methyl dihydrojasmonate.

Synthesis and Characterization of New Enantiopure 7,7′-Disubstituted 2,2′-Dihydroxy-1,1′-binaphthyls: Useful Ligands for the Asymmetric Allylation Reaction of Aldehydes

As an extension of our interest in developing new enantioselective reactions based on the binaphthol privileged ligand, we report a simple approach to the synthesis of 7,7′-disubstituted binaphthols. The commercially available 1,7-dihydroxynaphthalene (1) was used as starting material for the preparation of the bromoderivatives 2, which were oxidatively coupled to afford 3, a key intermediate for the preparation of a variety of enantiopure substituted binaphthols (8, 10). The absolute configuration of the new compounds was established by chiroptical analysis and by cholesteric induction. The optically active catalysts derived from the ligands 3, 8, 10, 16 and 17, complexed with Ti(OiPr)2Cl2, Zr(OiPr)4 and ZrCl4(THF)2, were employed for the enantioselective addition of allyltributyltin to aldehydes. Finally, the influence of the substituents of the binaphthyl core on the transmission of the chiral information was also investigated.

Synthesis and Characterization of New Enantiopure 7,7′-Disubstituted 2,2′-Dihydroxy-1,1′-binaphthyls: Useful Ligands for the Asymmetric Allylation Reaction of Aldehydes

European Journal of Organic ChemistryVolume 2000, Issue 7 p. 1375-1375 Correction Synthesis and Characterization of New Enantiopure 7,7′-Disubstituted 2,2′-Dihydroxy-1,1′-binaphthyls: Useful Ligands for the Asymmetric Allylation Reaction of Aldehydes Marco Bandini, Marco Bandini Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorSonia Casolari, Sonia Casolari Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorPier Giorgio Cozzi, Pier Giorgio Cozzi Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorGloria Proni, Gloria Proni Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, ItalySearch for more papers by this authorErick Schmohel, Erick Schmohel Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorGian Piero Spada, Gian Piero Spada gpspada@alma.unibo.it Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, ItalySearch for more papers by this authorEmilio Tagliavini, Emilio Tagliavini Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorAchille Umani-Ronchi, Achille Umani-Ronchi umani@ciam.unibo.it Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this author Marco Bandini, Marco Bandini Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorSonia Casolari, Sonia Casolari Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorPier Giorgio Cozzi, Pier Giorgio Cozzi Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorGloria Proni, Gloria Proni Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, ItalySearch for more papers by this authorErick Schmohel, Erick Schmohel Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorGian Piero Spada, Gian Piero Spada gpspada@alma.unibo.it Dipartimento di Chimica Organica “A. Mangini”, Università di Bologna, Via S. Donato 15, I-40127 Bologna, ItalySearch for more papers by this authorEmilio Tagliavini, Emilio Tagliavini Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this authorAchille Umani-Ronchi, Achille Umani-Ronchi umani@ciam.unibo.it Dipartimento di Chimica “G. Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna, ItalySearch for more papers by this author First published: April 2000 https://doi.org/10.1002/1099-0690(200004)2000:7<1375::AID-EJOC1375>3.0.CO;2-VAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume2000, Issue7April 2000Pages 1375-1375 RelatedInformation