Double take: β-Borylallylsilanes have been synthesized by the regioselective silaboration of terminal alkynes followed by palladium-catalyzed double-bond migration of the resulting β-borylalkenylsilanes. The stereoselectivity of the double-bond migration can be controlled by additives, thus leading to the stereocomplementary synthesis of (E)- and (Z)-β-borylallylsilanes.
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http://dx.doi.org/10.1002/anie.201106077 | DOI Listing |
Angew Chem Int Ed Engl
January 2025
University of Bonn: Rheinische Friedrich-Wilhelms-Universitat Bonn, Kekulé Institute for Organic Chemistry and Biochemistry, Gerhard-Domagk-Straße 1, 53121, Bonn, GERMANY.
Taxa-4,11-diene is made by the taxa-4,11-diene synthase (TxS) from Taxus brevifolia. The unique reactivity of the taxane system is characterised by long distance hydrogen migrations in the biosynthesis. This study demonstrates that selective long range hydrogen migrations also play a role in the high energy process of the EI-MS fragmentation of taxa-4,11-diene.
View Article and Find Full Text PDFMar Drugs
December 2024
G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, Pr. 100-letya Vladivostoka 159, 690022 Vladivostok, Russia.
Five new non-holostane di- and trisulfated triterpene pentaosides, conicospermiumosides A-1 (), A-2 (), A-3 (), A-1 (), and A-2 () were isolated from the Far Eastern sea cucumber Levin et Stepanov (Cucumariidae, Dendrochirotida). Twelve known glycosides found earlier in other species were also obtained and identified. The structures of new compounds were established on the basis of extensive analysis of the 1D and 2D NMR spectra, as well as by the HR-ESI-MS data.
View Article and Find Full Text PDFPolymers (Basel)
October 2024
Institute of Chemistry, St. Petersburg, St. Petersburg State University, 198504 St. Petersburg, Russia.
The development of biomaterials with gradient surface modification capable of spatially controlled cell adhesion and migration is of great importance for tissue engineering and regeneration. In this study, we proposed a method for the covalent modification of PLA-based materials with a cationic polypeptide (polylysine, PLys) via a thiol-ene click reaction carried out under a light gradient. With this aim, PLA-based films were fabricated and modified with 2-aminoethyl methacrylate (AEMA) as a double bond source.
View Article and Find Full Text PDFNat Commun
October 2024
State Key Laboratory of Fine Chemicals, School of Chemistry, Dalian University of Technology, Dalian, 116024, China.
The challenging synthesis of thermodynamic-unfavored cis-olefins through catalytic cross-coupling reactions requires the synergistic interaction of substrate-activating units and configuration-regulating catalysts. Successfully hitting these two birds with one stone, we herein develop a convenient photoredox access to Z-alkenes from alkynes and light alkanes with a bifunctional iron-catalyzed system possessing both C(sp)-H activation and configuration-controlling abilities. The protocol exhibits 100% atom utilization, mild conditions, a broad substrate scope, and compatibility with multitudinous functional groups.
View Article and Find Full Text PDFJ Mass Spectrom
October 2024
Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Canada.
The unimolecular reactions of protonated myrcene and linalool were investigated by collision-induced dissociation and density functional theory calculations. Experiments on a triple quadrupole mass spectrometer showed that protonated myrcene undergoes two major unimolecular reactions losing propene and isobutene, and two minor reactions of ethene and propane loss. In each case, the product ion consists of a substituted five-member ring.
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