Small ring compounds are fascinating molecules and have been used as valuable compounds in organic synthesis. In this study, a carborane-fused four-membered boracycle bearing an electron precise B-B bond, 1,2-[BBrSMe]--CBH, was synthesized the reaction of 1,2-Li--carborane with BBr(SMe). This novel boracycle can be used as a "strain-release" compound to achieve diboration of alkenes and alkynes, leading to the generation of ring-expansion products. Interestingly, when bis(trimethylsilyl) acetylene was employed, an allene-functionalized six-membered boracycle was obtained. Moreover, DFT calculations were conducted to shed light on the reaction mechanism.
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http://dx.doi.org/10.1039/d1dt03665c | DOI Listing |
Org Lett
December 2024
College of Sciences, Hebei University of Science and Technology, Shijiazhuang 050022, China.
A practical and efficient -diboration of propargyl alcohols was accomplished using sodium hydride (NaH) as a base in ,-dimethylformamide at room temperature. The mild reaction conditions demonstrate general applicability, facilitating the successful conversion of both terminal and internal propargyl alcohols with diverse structures and functional groups into highly functionalized alkenediboronates [4-borylated 1,2-oxaborol-2(5)-oles]. The resulting products, which incorporate two boron groups, can be selectively activated and subjected to stepwise transformations, thereby providing an effective platform for synthesizing a wide range of structurally diverse trisubstituted alkenes.
View Article and Find Full Text PDFOrg Lett
November 2024
Division of Applied Chemistry, Okayama University, Tsushimanaka, Okayama 700-8530, Japan.
A novel method for the two-step synthesis of α-boryl-α-substituted allylboronates from propyne is described. These allylboronates are prepared by the Co-catalyzed 1,1-diboration reaction of propyne with Bpin, followed by the base-mediated alkylation reaction of 1,1-di(boryl)propene at the α-position. Computational studies revealed the origins of observed reactivity and selectivity in the base-mediated alkylation reaction.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
School of Chemistry, University of Bristol, Cantock's Close, BS8 1TS, Bristol, UK.
Asymmetric diboration of terminal alkenes is well established, and subsequent selective functionalization of the less hindered primary boronic ester is commonly achieved. Conversely, selective functionalization of the sterically less accessible secondary boronic ester remains challenging. An alternative way to control chemoselective functionalization of bis(boron) compounds is by engendering different Lewis acidity to the two boryl moieties, since reactivity would then be dictated by Lewis acidity instead of sterics.
View Article and Find Full Text PDFChem Sci
May 2023
Institut für Anorganische und Analytische Chemie, Goethe-Universität Frankfurt Max-von-Laue-Straße 7 D-60438 Frankfurt am Main Germany
Diboration and silaboration reactions are prominent tools to introduce valuable functional groups into organic substrates. To date, most diboranes(4) and silylboranes used for this purpose are electronically and/or kinetically stabilized and require activation by a catalyst. We show here that the tetraaryl (μ-hydrido)diborane(4) anion [3] and the silyl (hydrido)borate ([4])/MeSiBr system react spontaneously with the archetypal olefin ethylene in the absence of a catalyst.
View Article and Find Full Text PDFJ Am Chem Soc
February 2023
Max-Planck-Institut für Kohlenforschung, 45478 Mülheim/Ruhr, Germany.
The dinoflagellate-derived polyether prorocentin is a co-metabolite of the archetypical serine/threonine phosphatase inhibitor okadaic acid. Whereas a structural relationship cannot be missed and a biosynthetic link was proposed, it is currently unknown whether there is any parallel in the bioactivity profile of these natural products. However, it was insinuated in the past that the structure assigned to prorocentin might need to be revised.
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