Metal-catalyzed cycloisomerization of 1,n-enynes has appeared as a highly attractive methodology for the synthesis of original carbo- and heterocycles. This chapter intends to propose an overview of the recent and seminal advances in 1,n-enynes cycloisomerization reactions in the presence of carbophilic transition metals. The recent mechanistic insights, the enantioselective versions, and the applications in total synthesis are highlighted.
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http://dx.doi.org/10.1007/128_2010_116 | DOI Listing |
Org Lett
December 2024
Omura Satoshi Memorial Institute and Graduate School of Infection Control Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo 108-8641, Japan.
The avermectins make up a biologically relevant class of complex natural products that continue to inspire the development of new strategies in chemical synthesis. Herein, we disclose a concise synthesis of the southern core of avermectin aglycon. The key hydrobenzofuran was forged by either reductive cyclization or cycloisomerization, both using a cationic palladium precatalyst.
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December 2024
Tokyo Institute of Technology: Tokyo Kogyo Daigaku, Department of Chemistry, 2-12-1-E1-4 Ookayama, Meguro-ku, 152-8551, Tokyo, JAPAN.
Helical fused anthracenes were elongated by fusing additional aromatic units at both ends to yield novel expanded helicenes. Compounds [5]HA2N and [7]HA consisting of 19 and 21 benzene rings, respectively, were synthesized by fourfold cycloisomerization of the corresponding terminal alkyne precursors. The helical structures were confirmed by X-ray crystallographic analysis, where the aromatic frameworks stacked effectively with the helical turn numbers exceeding two.
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December 2024
Key Laboratory of the Ministry of Education for Advanced Catalysis Materials, College of Chemistry and Materials Science, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China.
An unexpected cascade reaction of enyne-amides with sulfur-ylides has been developed. This cascade reaction involves cycloisomerization, dearomatic cyclopropanation, ring-opening rearomatization, and subsequent cyclopropanation, differing from the common [2 + n] cyclization of enyne-amides. A variety of (spirocyclopropane)dihydrofuran derivatives have been efficiently and conveniently synthesized in a single vessel, exhibiting excellent diastereoselectivity and good functional group tolerance.
View Article and Find Full Text PDFJACS Au
November 2024
Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
(-)-Bipolarolide D is an ophiobolin-derived sesteterpenoid with a unique tetraquinane (5/5/5/5) tetracyclic skeleton decorated with a diverse set of functionalities. Herein we report a robust, scalable, and efficient total synthesis of this natural product in 1.8% overall yield.
View Article and Find Full Text PDFMolecules
November 2024
Department of Pharmacy, Showa Pharmaceutical University, Machida 194-8543, Japan.
Gold-catalyzed propargylic substitution of propargylic alcohols with 1,3-dicarbonyl compounds followed by cycloisomerization in ionic liquid enables the environmentally friendly synthesis of polysubstituted furans in good-to-high yields. The reaction proceeds via the hydrated propargylic substitution product . The gold catalyst can be recycled at least three times.
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