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In this report, we describe a halo-Prins/aryl halo-Nazarov cyclization strategy that employs readily available starting materials, inexpensive reagents, and convenient reaction procedures to generate functionalized haloindenes and indanones. The scope and limitations of the method are outlined, demonstrating that aromatic systems readily react under mild, catalytic conditions when this strategy is implemented. Furthermore, we present both experimental and computational data supporting the notion that cyclizations of 3-halopentadienyl cationic intermediates are more kinetically accessible, as well as more thermodynamically favorable, than cyclizations of the analogous 3-oxypentadienyl cationic systems. The energetic advantage imparted by the halo-Nazarov cyclization design was found to be especially valuable in the cyclizations of arylallyl cationic intermediates, which require disruption of aromaticity.
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http://dx.doi.org/10.1021/jacs.9b00198 | DOI Listing |
J Am Chem Soc
July 2025
Department of Chemistry, University of Rochester, 120 Trustee Rd, Rochester, New York 14627, United States.
The first successful fragment coupling/cationic cascade approach for the synthesis of a complex indoloditerpenoid tubingensin A is described. The synthesis is the first example of a novel disconnection strategy targeting a central quaternary carbon locus. A -Prins/-Nazarov cationic cascade sequence enabled the rapid preparation of a complex intermediate as a single diastereomer, containing the vicinal quaternary centers found in the backbone stereotriad.
View Article and Find Full Text PDFEuropean J Org Chem
November 2024
Department of Chemistry, University of Rochester, Rochester, NY 14627.
This manuscript describes a study of diverse reaction outcomes that stem from the ionization of -alkynyl-Prins adducts. Experimental results have demonstrated unexpected behavior in the nitrogen-containing systems compared to the analogous oxygen derivatives derived from -Prins/-Nazarov sequences. In-depth experimental studies and computational analysis revealed an intricate mechanism involving competing -Nazarov and -Nazarov pathways.
View Article and Find Full Text PDFChem Sci
May 2023
Department of Chemistry, University of Rochester Rochester NY USA 14627-0216
The nitrogen-interrupted Nazarov cyclization can be a powerful method for the stereocontrolled synthesis of sp-rich -heterocycles. However, due to the incompatibility between the basicity of nitrogen and the acidic reaction conditions, examples of this type of Nazarov cyclization are scarce. Herein, we report a one-pot nitrogen-interrupted -Prins/-Nazarov coupling cascade that joins two simple building blocks, an enyne and a carbonyl partner, to furnish functionalized cyclopenta[]indolines with up to four contiguous stereocenters.
View Article and Find Full Text PDFOrg Lett
March 2021
Department of Chemistry, University of Rochester, 120 Trustee Road, Rochester, New York 14611, United States.
In this report, we describe an alkynyl --Prins cyclization of 3-hydroxyisoindolones to prepare -Prins products. These Prins adducts undergo oxidation at the 3-isoindolone position after activation of the amide by triflic anhydride and 2-chloropyridine to form a pentadienyl cation capable of undergoing a -Nazarov cyclization. Using this methodology, angular-fused N-heterocyclic small molecules with two new rings, two new carbon-carbon bonds, a vinyl halide, and an -tertiary stereocenter can be obtained in good yields.
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