Herein, a Sc(OTf)-catalyzed (3+2) annulation of 2-indolylmethanols with propargylic alcohols is reported. The reaction proceeds via a Friedel-Crafts-type allenylation/5-exo-annulation cascade. In the reaction, 2-indolylmethanol is used as a three-carbon synthon, and propargyl alcohol is used as a two-carbon synthon. This method provides a direct and high-yield pathway for synthetically useful cyclopenta[]indoles. In general, the method features easily accessible substrates with broad scope and generality, the formation of multiple bonds with high efficiency, and easy scale-up.
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http://dx.doi.org/10.3390/molecules29061251 | DOI Listing |
Chem Commun (Camb)
January 2025
Institute of Medicine and Materials Applied Technologies, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu, Shandong 273165, China.
A mild and efficient [3+2] annulation of phenidones with propiolates has been developed to access -substituted indole alkylamides, enabled by merging electrochemistry with iridium catalysis using an undivided cell at room temperature. The mechanistic studies have confirmed that the electrochemically mediated catalytic cycle of Ir-Ir-Ir exhibits enhanced efficiency, mild reaction conditions, and unconventional selectivity.
View Article and Find Full Text PDFJ Am Chem Soc
January 2025
Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, Málaga 29071, Spain.
Azuacenes, defined as azulene fused with acenes in a 6-7-5 ring topology and spanning lengths from 3 to 6 rings, have been synthesized using a new skeleton editing and [3 + 2] annulation synthesis protocol as a distinction regarding the procedures to obtain the 6-5-7 isomers. Comprehensive studies on ground-state and excited-state spectroscopy, electrochemical properties, chemical stability, and solid-state structure have been conducted to compare these azuacenes with acenes. For the same number of rings, we found that azuacenes improve the chemical stability of acenes (i.
View Article and Find Full Text PDFMolecules
December 2024
School of Material Science and Engineering, Dalian Jiaotong University, Dalian 116028, China.
An effective method for the construction of functionalized indolizines has been developed in which β,β-difluoro peroxides act as novel C2-building blocks to implement [3+2] annulation with pyridinium ylides under base-mediated conditions. With this protocol, a broad range of multisubstituted indolizines were prepared in moderate to good yields under mild conditions, and many useful functional groups were tolerated.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
RIKEN, Organometallic Chemistry Laboratory, 2-1 Hirosawa, 351-0198, Wako, Saitama, JAPAN.
The enantioselective [3+2] annulation of readily accessible aldimines with alkynes via C-H activation is, in principle, a straightforward and atom-efficient route for synthesizing chiral 1-aminoindenes, which are important components in a wide array of natural products, bioactive molecules, and functional materials. However, such asymmetric transformation has remained undeveloped to date due to the lack of suitable chiral catalysts. Here, we report for the first time the enantioselective [3+2] annulation of aldimines with alkynes via C-H activation using chiral half-sandwich scandium catalysts.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Department of Chemistry, College of Sciences, Tianjin University of Science and Technology, Tianjin 300457, People's Republic of China.
A sequential [3 + 2]/[2 + 1] annulation reactions of benzimidazole- and indole-derived acrylonitriles with vinylsulfonium salts have been developed for the first time, and shown to provide in yields of 32 to 98% a series of azabicyclo[3.1.0]hexanes containing each a cyano-substituted tetrasubstituted carbon stereocenter with >20 : 1 dr.
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