Two new bicyclobutanes were prepared from cyclobutyl systems by a novel, solvolytic, carbocation-based methodology. An electron-withdrawing perfluoroalkyl group at the incipient cationic center enhances neighboring-group participation of the γ-silyl group, inducing facile, remarkably selective 1,3-elimination yielding only bicyclobutanes. The method unlocks potential access to a host of EWG-substituted strained rings and a potential new method for the synthesis of trifluoromethylcyclopropanes.
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http://dx.doi.org/10.1021/ol200121f | DOI Listing |
J Am Chem Soc
January 2025
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Graft-through ring-opening metathesis polymerization (ROMP) of norbornene-terminated macromonomers (MMs) prepared using various polymerization methods has been extensively used for the synthesis of bottlebrush (co)polymers, yet the potential of ROMP for the synthesis of MMs that can subsequently be polymerized by graft-through ROMP to produce new bottlebrush compositions remains untapped. Here, we report an efficient "ROMP-of-ROMP" method that involves the synthesis of norbornene-terminated poly(norbornene imide) (PNI)-based MMs that, following ROMP, provide new families of bottlebrush (co)polymers and "brush-on-brush" hierarchical architectures. In the bulk state, the organization of the PNI pendants drives bottlebrush backbone extension to enable rapid assembly of asymmetric lamellar morphologies with large asymmetry factors.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
CAS Key Laboratory of Science and Technology on Applied Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
Well-defined single-atom catalysts (SACs) serve as ideal model systems for directly comparing experimental results with theoretical calculations, offering profound insights into heterogeneous catalytic processes. However, precisely designing and controllably synthesizing SACs remain challenging due to the unpredictable structure evolution of active sites and generation of embedded active sites, which may bring about steric hindrance during chemical reactions. Herein, we present the precious nonpyrolysis synthesis of Re SACs with a well-defined phenanthroline coordination supported by NiO (Re-phen/NiO).
View Article and Find Full Text PDFChem Asian J
January 2025
Zunyi Medical University, School of Pharmacy, CHINA.
N-acyl/sulfonyl-α-phosphonated 1,2,3,4-tetrahydroiso-quinolines (THIQs) are highly important structural motifs in organic synthesis and drug discovery. However, the one-pot approach enabling direct difunctionalization of THIQs remains challenging. Herein we report a photomediated one-pot multicomponent cascade reaction to access N-acyl/sulfonyl-α-phosphonated THIQs via twice acyl/sulfonyl iminium.
View Article and Find Full Text PDFOrg Lett
January 2025
Key Laboratory of Drug-Targeting and Drug Delivery System of the Education Ministry, Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
Dehydrophenylalanine has a characteristic unsaturated double bond that makes it indispensable in the context of peptides and proteins. In this study, we report the Pd-catalyzed C(sp)-H arylation of dehydroalanine-containing peptides with arylthianthrenium salts under mild and base free conditions, which provides efficient access to dehydrophenylalanine-containing peptides. This approach enables the efficient coupling of different drug scaffolds and bioactive molecules to the peptides.
View Article and Find Full Text PDFChemistry
January 2025
The University of Manchester, Manchester Institute of Biotechnology, 131 Princess Street, M1 7DN, Manchester, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND.
The natural product synthesis of brevione J undergoes a cascade of reactions including an oxidative desaturation and a ring-expansion. The C1-C2 desaturation of brevione B is catalyzed by the nonheme iron dioxygenase BrvJ using one molecule of O2 and a-ketoglutarate (aKG). However, whether the subsequent oxidative ring expansion reaction is also catalyzed by the same enzyme is unknown and remains controversial.
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