A novel, green and efficient method is developed for the synthesis of methylene bridged bis(indolyl)methanes in good to excellent yields. The reaction employs methyl tert-butyl ether (MTBE) as the methylene source and selectfluor as an oxidizing agent. The scope and versatility of the methods have been successfully demonstrated with 48 examples. The metal-free transformation process is suitable for scale-up production. A selectfluor-promoted oxidative reaction mechanism is proposed based on the results of the experimental studies.
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http://dx.doi.org/10.1039/d1ob00120e | DOI Listing |
Chem Rec
January 2025
Department of Chemistry, Jadavpur University, 188, Raja Subodh Chandra Mallick Rd, Jadavpur, Kolkata, West Bengal, 700032, India.
Selectfluor, [1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate)], is a highly valuable reagent in contemporary chemistry, serving not only as an electrophilic fluorinating agent but also as an effective catalyst in the synthesis of various pharmaceutically relevant heterocycles.
View Article and Find Full Text PDFChem Sci
December 2024
College of Chemistry, Pingyuan Laboratory, Zhengzhou University 100 Science Avenue Zhengzhou 450001 Henan China
Herein, we demonstrate a practical dual ligand-enabled iron photocatalysis paradigm-converting all kinds of halogen-containing carboxylates (C X COO, X: F, Cl, Br) into C X radicals for the valuable chloro/fluoro-polyhaloalkylation of non-activated alkenes with easily available trichloroacetonitrile/Selectfluor as the electrophilic halogenation reagent. The modular assembly of the effective iron and C X COO-based light-harvesting species using the two ligands-OMe/CF-substituted bipyridine and acetonitrile/trichloroacetonitrile is evidenced by detailed mechanistic studies. The late-stage modification, low loading amount of iron (TON: 257) and feasible gram-scale synthesis show the utility of this protocol.
View Article and Find Full Text PDFOrg Lett
November 2024
Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo, Kyoto 606-8501, Japan.
A metal-free and mild cleavage of tertiary -methoxybenzyl amides (PMB -amide) under photoredox conditions is developed using Mes-Acr-PhBF and Selectfluor to activate the electron-rich benzylic C-H bond of the PMB moiety. The resulting acyl fluoride intermediate is versatile and facilitates a one-pot transamidation of the PMB -amide. The value of this protocol is highlighted by performing the chemoselective activation of the PMB -amide in bifunctional molecules containing more reactive functionalities than the amide.
View Article and Find Full Text PDFJ Am Chem Soc
April 2024
Department of Chemistry, Emory University, Atlanta, Georgia 30322, United States.
Lysine dimethylation (Kme) is a crucial post-translational modification (PTM) that regulates biological processes and is implicated in diseases. There is significant interest in globally identifying these methylation marks. Unfortunately, this remains challenging due to the lack of robust technologies for selectively labeling Kme.
View Article and Find Full Text PDFJ Org Chem
February 2023
School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
We describe an efficient method for benzylic C-H fluorination via sequential hydrogen-atom transfer (HAT) and oxidative radical-polar crossover utilizing the Ag(I)/Selectfluor system. Amide ligands, such as benzamide and sulfonamide, substantially facilitate the processes leading to a carbocation intermediate, which subsequently reacts with nucleophilic fluorinating reagent to form a C-F bond. This protocol is applicable to the fluorination of all 1°, 2°, and 3° C-H bonds as well as to late-stage C-H fluorination of bioactive molecules.
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