An asymmetric addition/cyclization cascade of amidoesters and iminoquinones is developed using noncovalent N-heterocyclic carbene (NHC) catalysis. The process enables access to various functionalized benzofuranones with an all-carbon quaternary stereocenter with high yields and ee values. The reaction displays a broad substrate scope. Via product modifications, enantioenriched synthesis of biologically relevant spirocyclic lactones and lactams is achieved. Substrate activation via noncovalent interaction with NHC is suggested for the process.
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http://dx.doi.org/10.1021/acs.orglett.4c03014 | DOI Listing |
Org Biomol Chem
January 2025
School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China.
A visible-light-induced deoxygenative alkylation/cyclization of acrylamides with alcohols activated by CS has been developed by using xanthate salts as alkyl radical precursors in the presence of tricyclohexylphosphine. It proceeds through a tandem radical addition/cyclization process, and this protocol provides a reliable and practical approach to building the skeleton of 3,3-disubstituted oxindoles in moderate to good yields. Notable features of this reaction include readily available starting reagents, broad substrate scope and mild reaction conditions.
View Article and Find Full Text PDFJ Org Chem
December 2024
State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. China.
J Org Chem
November 2024
Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal 462066, India.
Herein, we disclose a cinchona-alkaloid-based squaramide-catalyzed intermolecular oxa-Michael cascade addition cyclization of -protected hydroxyl amine to formyl-tethered Michael acceptors toward the synthesis of enantioenriched 1,2-oxazine scaffolds. Generally, good yield (up to 78%), good to excellent enantiomeric ratio (up to 98:2 er), and excellent regioselectivity (>19:1) were observed. Furthermore, the scalability of this methodology and a successful demonstration of postsynthetic transformations have been accomplished.
View Article and Find Full Text PDFJ Org Chem
November 2024
School of Basic Medical Sciences, Xinxiang Medical University, Xinxiang, Henan 453003, P. R. China.
We disclose herein an efficient and facile method for the synthesis of SF-containing isoquinolinediones with an all-carbon quaternary stereocenter via intramolecular pentafluorosulfanylation of acrylamides using SFCl as a pentafluorosulfanylation reagent. The protocol proceeds under mild reaction conditions and enjoys a broad substrate scope, wide functional group compatibility, and high atom- and step-economy. A radical mechanism involving the SF radical cascade addition/cyclization of acrylamides is proposed.
View Article and Find Full Text PDFOrg Lett
October 2024
School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700032, India.
An asymmetric addition/cyclization cascade of amidoesters and iminoquinones is developed using noncovalent N-heterocyclic carbene (NHC) catalysis. The process enables access to various functionalized benzofuranones with an all-carbon quaternary stereocenter with high yields and ee values. The reaction displays a broad substrate scope.
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