A metal-free and efficient approach for the synthesis of structurally important nicotinates through 4-HO-TEMPO-mediated [3 + 3] annulation of cyclopropanols with β-enamine esters is presented. This protocol features high atom efficiency, green waste, simple operation and broad substrate scope. Moreover, the experiments of gram-scale synthesis and recovery of oxidants make this strategy more sustainable and practical.
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http://dx.doi.org/10.1039/d3ob01662e | DOI Listing |
Org Biomol Chem
June 2024
School of Chemistry and Chemical Engineering, Suzhou University, Suzhou, Anhui 234000, People's Republic of China.
Transition metal catalyzed C-H bond activation has become one of the most important tools for constructing new chemical bonds. Introducing directing groups to the substrates is the key to a successful reaction, these directing groups can also be further transformed in the reaction. Amidines with their unique structure and reactivity are ideal substrates for transition metal-catalyzed C-H transformations.
View Article and Find Full Text PDFOrg Biomol Chem
November 2023
Institute of Bioorganic Chemistry Russian Academy of Sciences, Miklukho-Maklaya 16/10, 117997, Moscow, Russia.
2-Allyloxybenzaldehydes undergo [2 + 1] cycloadditions under 365 nm LED irradiation to form the corresponding chroman-fused cyclopropanols. The reaction proceeds easily without any catalysts or additives in dimethyl sulfoxide.
View Article and Find Full Text PDFOrg Biomol Chem
November 2023
State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, P. R. China.
A metal-free and efficient approach for the synthesis of structurally important nicotinates through 4-HO-TEMPO-mediated [3 + 3] annulation of cyclopropanols with β-enamine esters is presented. This protocol features high atom efficiency, green waste, simple operation and broad substrate scope. Moreover, the experiments of gram-scale synthesis and recovery of oxidants make this strategy more sustainable and practical.
View Article and Find Full Text PDFChem Sci
September 2018
Division of Chemistry and Biological Chemistry , School of Physical and Mathematical Sciences , Nanyang Technological University, Singapore 637371 , Singapore . Email:
Cobalt-diphosphine catalysts promote ring-opening coupling reactions between cyclopropanols and unactivated internal alkynes, affording either β-alkenyl ketones or multisubstituted cyclopentenol derivatives in good yields with good to excellent regioselectivities. The chemoselectivity between these β-alkenylation and [3 + 2] annulation reactions, which likely share a cobalt homoenolate as a key catalytic intermediate, is exquisitely controlled by the reaction conditions, with the solvent being a major controlling factor. The reactions are proposed to involve ring opening of cobalt cyclopropoxide into homoenolate, migratory insertion of the alkyne into the Co-C bond, and protodemetalation or intramolecular carbonyl addition of the resulting alkenylcobalt species.
View Article and Find Full Text PDFOrg Lett
December 2015
Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, United States.
A new method for seven-membered ring annulation has been devised by an intramolecular cross-coupling of cyclopropanols and aryl/alkenyl halides. This cyclization reaction is broad in scope and provides easy access to not only fused but also bridged bicyclic compounds.
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