Chemical synthesis of lantibiotic analogues wherein monosulfide bridges are replaced with other groups can shed light on structure-activity relationships and generate variants that are resistant to aerobic oxidation and have better metabolic stability. This work describes the first complete synthesis of a carbocyclic lantibiotic analogue 2, using sequential on-resin ring-closing olefin metathesis and solution-phase peptide synthesis. The methodology described should find wide application for the preparation of rigidified peptidomimetics containing multiple carbocyclic rings. [structure: see text].
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/ol063133j | DOI Listing |
Phys Chem Chem Phys
December 2024
Department of Chemistry, Visva-Bharati University, Santiniketan, West Bengal-731235, India.
First-principles analyses were performed for understanding the mechanistic details of Fe-catalysed asymmetric hydrogenation of alkenes in the presence of silane that has recently been experimentally realized. The catalytic hydrogenation is expected to proceed through initial hydride transfer from Fe-H to the CC bond of alkene, followed by σ-bond metathesis of hydrosilane to afford a chiral alkane product and an iron silyl species, which then reacts with H to regenerate the iron hydride species another σ-bond metathesis. The mechanistic details and the origin of the regioselectivity and stereoselectivity of these reactions are understood on the basis of detailed potential energy surface analysis, charge transfer and noncovalent interactions involved therein, strain energy and isodesmic studies in the solvated stage.
View Article and Find Full Text PDFDalton Trans
December 2024
Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, Heidelberg 69120, Germany.
Bis(catecholato)silanes were showcased as strong Lewis acids, while their inherent redox activity remained unexplored in this context. In the present work, we study the oxidation of monomeric bis(3,6-di--butyl-catecholato)silane (1), leading to the Lewis superacidic radicalic silylium ionradical 1˙+ (FIA 784 kJ mol). Oxidation of 1 with [N(-CHBr)][B(CF)] yielded [1][B(CF)], displaying strong catalytic activity in the Friedel-Crafts-dimerization, hydrodeoxygenation and carbonyl-olefin-metathesis.
View Article and Find Full Text PDFJ Org Chem
December 2024
College of Pharmacy & Graduate School of Pharmaceutical Sciences, Ewha Womans University, 52 Ewhayeodae-gil, Seodaemun-Gu, Seoul 03760, Republic of Korea.
The concise and efficient total synthesis of (±)-tetraponerine-2 () and (±)-tetraponerine-4 () was achieved in 9% and 14% overall yield, respectively. The key step included the diastereoselective gold(I)-catalyzed intramolecular dehydrative amination of an allylic alcohol-tethered sulfamide to produce the 1,3-diamine moiety. The resulting olefinic side chain was then elaborated by cross-metathesis and cyclized to a five-membered pyrrolidine or a six-membered piperidine ring by intramolecular Mitsunobu -alkylation.
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
Department of Chemistry and Applied Biosciences, Laboratory of Organic Chemistry, ETH Zurich, Zurich 8093, Switzerland.
Methyltrioxorhenium (MTO) supported on AlO or SiO-AlO is an efficient heterogeneous alkene metathesis catalyst that works at room temperature and tolerates various functional groups. Surface studies found that MTO interacts with highly Lewis-acidic aluminum centers and that its methyl group is probably C-H activated resulting in rhenium-methylidene species. The exact structure of the catalyst resting state and the active species is subject to scientific debate.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, Tokyo 113-0032, Japan.
While ring-closing metathesis (RCM) is a powerful method for constructing medium and large cyclic alkenes, its application to the synthesis of heterocycles faces considerable limitations. For instance, RCM of divinyloxyalkanes does not proceed under the conventional conditions of RCM. The challenge lies in the formation of stable Fischer-type carbene intermediates with heteroatom(s) bound to the carbene carbon, impeding subsequent metathesis.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!