Bridgehead metallation is possible in a ketone having the welwistatin skeleton, and this facilitates installation of the isothiocyanate function present in the natural product, and also enables synthesis of remarkable bridgehead alkenes.
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http://dx.doi.org/10.1039/b820674k | DOI Listing |
Org Lett
May 2024
Department of Chemistry, University of Houston, Houston, Texas 77204, United States.
Computational studies for a series of low to high strain anti-Bredt alkenes suggest that those with highly twisted bridgehead double bonds and a small singlet-triplet energy gap may undergo facile stepwise [2 + 2] cycloadditions to furnish four membered rings. A selection of reaction substrates, including ethylene, acetylene, perfluoroethylene, and cyclooctyne are considered.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
July 2023
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
Novel P,O-type ligands, N-disulfonyl bicyclic bridgehead phosphorus triamides, were synthesized and utilized in Pd-catalyzed hydrosilylation involving tertiary silanes, unactivated alkenes, and conjugated dienes. The ligand displayed a remarkable level of reactivity for alkene hydrosilylation with tertiary silanes and its use resulted in a significant improvement in the regioselectivity of diene hydrosilylation towards 1,2-hydrosilylation. X-ray crystallographic analysis confirmed the bidentate nature of the ligand, with coordination of phosphorus and oxygen.
View Article and Find Full Text PDFJ Am Chem Soc
April 2023
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan.
CH isomers not only serve as a basis to understand the chemical properties of hydrocarbons but are possible intermediates in combustion and organic reactions in outer space. Cyclobutenylidene (CBY), an elusive CH isomer, is often proposed as a key intermediate in transition-metal-catalyzed metathesis and cycloaddition reactions between carbon-carbon multiple bonds. The geometrical structure of cyclobutenylidene predicted by calculations had been debated as whether it should be regarded as a carbocyclic carbene or a strained bridgehead alkene.
View Article and Find Full Text PDFOrg Lett
July 2022
School of Pharmaceutical Sciences, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China.
Herein, we report a novel bioorthogonal reaction that hinges on a bridgehead alkene (BHA)-enabled inverse-electron-demand Diels-Alder (IEDDA) cycloaddition. Readily accessible from natural product β-caryophyllene, the strained BHA displays high reactivity toward the IEDDA reaction while maintaining excellent biocompatibility. The developed IEDDA reaction has been applied to protein labeling and pretargeted live cell imaging.
View Article and Find Full Text PDFOrg Lett
July 2022
Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
A two-step synthesis of geminal divinyl compounds from ketones was developed. An allyl titanium reagent prepared from 1-phenylthio-4-trimethylsilyl-2-butene was reacted with a ketone, and the resulting tertiary alcohol was subjected to a Brønsted acid-mediated rearrangement reaction to generate a geminal divinyl compound. Introduction of another alkene moiety followed by ring closing metathesis resulted in a bicyclic compound possessing a vinyl group at the bridgehead position.
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