A novel, base-catalyzed and highly diastereoselective direct Michael addition-isomerization sequence is presented for the efficient synthesis of Rauhut-Currier-type adducts. An unexpected α-addition of γ-butyrolactam onto the 3-acyl coumarin derivatives was observed rather than the γ-addition, which is more common. The adducts could further undergo hydrolysis/decarboxylation to generate the products which are equivalent to those obtained by α-addition of γ-butyrolactam onto the corresponding chalcones.
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http://dx.doi.org/10.1021/acs.joc.6b02526 | DOI Listing |
J Org Chem
November 2024
Faculty of Sciences, Department of Chemistry, University of Chile, Las Palmeras 3425, Ñuñoa, 7750000 Santiago, Chile.
The synthesis of fused benzoxepines relies on the use of complex substrates and methodologies. Herein, we report our experimental and theoretical findings about an unprecedented Rauhut-Currier-type reaction catalyzed by CsCO to access these important compounds. The developed methodology avoids the use of phosphine- or amine-based catalysts and additives.
View Article and Find Full Text PDFAcc Chem Res
March 2023
School of Chemistry and Chemical Engineering, Key Laboratory of the Colloid and Interface Chemistry, Ministry of Education, Shandong University, Jinan 250100, China.
ConspectusThe exploration of new catalysis concepts and strategies to drive chemical reactions is of vital importance for the sustainable development of organic synthesis. Recently, chalcogen bonding catalysis has emerged as a new concept for organic synthesis and has been demonstrated to be an important synthetic tool capable of addressing elusive reactivity and selectivity issues. This Account describes our progress in the research field of chalcogen bonding catalysis, including (1) the discovery of phosphonium chalcogenide (PCH) as highly efficient chalcogen bonding catalyst; (2) the development of "chalcogen-chalcogen bonding catalysis" and "chalcogen···π bonding catalysis" modes; (3) the demonstration that chalcogen bonding catalysis with PCH can activate hydrocarbons to achieve cyclization and coupling reactions of alkenes; (4) the discovery of unusual results that chalcogen bonding catalysis with PCH can solve elusive reactivity and selectivity issues that are inaccessible by classic catalysis approaches; and (5) the elucidation of chalcogen bonding mechanisms.
View Article and Find Full Text PDFRSC Adv
November 2022
School of Petrochemical Engineering, Changzhou University Changzhou China
Catalytic asymmetric α-regioselective Michael additions of vinylogous α-ketoester enolate are described herein. With 0.1-1.
View Article and Find Full Text PDFBeilstein J Org Chem
July 2021
Institute for Chemistry and Technology of Materials, Graz University of Technology, Stremayrgasse 9, 8010 Graz, Austria.
Electron-rich triarylphosphines, namely 4-(methoxyphenyl)diphenylphosphine (MMTPP) and tris(4-trimethoxyphenyl)phosphine (TMTPP), outperform commonly used triphenylphosphine (TPP) in catalyzing oxa-Michael additions. A matrix consisting of three differently strong Michael acceptors and four alcohols of varying acidity was used to assess the activity of the three catalysts. All test reactions were performed with 1 mol % catalyst loading, under solvent-free conditions and at room temperature.
View Article and Find Full Text PDFJ Org Chem
February 2019
Department of Chemistry , Korea Advanced Institute of Science & Technology (KAIST), Daejeon 34141 , Korea.
We describe different modes of dimerization of various α',γ-dioxyenone derivatives with potential applications to the synthesis of high-order securinega alkaloids. We learned that the relative stereochemical relationship between α'- and γ-hydroxyl groups of the α',γ-dihydroxyenone derivative determines the mode of dimerization. While cis-α',γ-dioxyenone 26 provided the Rauhut-Currier-type (RC-type) dimer 31 upon reaction with TBAF, trans-α',γ-dihydroxyenone 34 afforded dimeric tetrahydrofuran derivative 41 under the same reaction conditions.
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