An efficient photocatalytic method was developed for the remote C5-H bond carboxylation of 8-aminoquinoline amide and sulfonamide derivatives. This methodology uses in situ generated CBr radical as a carboxylation agent with alcohol and is further extended to a variety of arenes and heteroarenes to synthesize the desired carboxylated product in moderate-to-good yields. The reaction proceeding through a single electron transfer pathway was established by a control experiment, and a butylated hydroxytoluene-trapped aryl radical cation intermediate in high-resolution mass spectrometry was identified.
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http://dx.doi.org/10.1021/acs.joc.9b00942 | DOI Listing |
Org Biomol Chem
April 2024
Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 13, 50019 Sesto Fiorentino, Florence, Italy.
Convenient synthesis of stereochemically dense 5-oxo-pyrrolidines was obtained from succinic anyhdride and imines by combining the Castagnoli-Cushman reaction with directed Pd-catalyzed C(sp)-H functionalization, taking advantage of the developing carboxylic group properly derivatized with 8-aminoquinoline as a directing group. These fully substituted 5-oxopyrrolidines were found to be able to inhibit BACE-1 enzyme with sub-micromolar activity, thanks to the interaction of the key aryl appendage introduced by C(sp)-H activation within BACE-1 S2' subsite.
View Article and Find Full Text PDFAcc Chem Res
November 2023
Department of Chemistry, National University of Singapore, 4 Science Drive 2, Republic of Singapore, 117544.
ConspectusEfficient construction of ubiquitous carbon-carbon bonds between two electrophiles has garnered interest in recent decades, particularly if it is mediated by nonprecious, first-row transition metals. Reductive coupling has advantages over traditional cross-coupling by obviating the need for stoichiometric air- and moisture-sensitive organometallic reagents. By harnessing transition metal-catalyzed reductive coupling as a powerful tool, intricate molecular architectures can be readily assembled through the installation of two C-C bonds across π systems (alkenes/alkynes) via reaction with two appropriate electrophiles.
View Article and Find Full Text PDFChem Asian J
June 2023
Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, 110016, India.
Herein, we report a palladium-catalyzed 'on-water' methodology for the synthesis of biaryl and m-teraryl derivatives of aryl carboxamides by selective mono and bis C-H bond functionalization. 8-aminoquinoline and 2-thiomethylaniline were used as directing groups for C-H bond functionalization of aryl carboxamides with various aryl and alkyl iodides using 3.0-4.
View Article and Find Full Text PDFChem Sci
January 2023
Department of Chemistry, Indian Institute of Technology Bombay Powai Mumbai 400076 India
Recent years have seen the emergence of transition metal catalyzed C-H activation as a powerful synthetic tool in organic chemistry. Allenes have fascinated synthetic chemists due to their unique reactivity. While directing group assisted functionalization of C(sp)-H bonds with allenes is well documented in the literature, their coupling with more challenging aliphatic C(sp)-H bonds remains elusive.
View Article and Find Full Text PDFChem Asian J
December 2022
Department of Chemistry, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, 110016, India.
A water-soluble bifunctional, bistate ruthenium catalyst has been developed using the 8-aminoquinoline ligand which responds to an acid-base stimuli and is catalytically active for two complementary reactions. The "Ru-amino state" is highly active for catalytic transfer hydrogenation of various aldehydes using formic acid as the hydrogen source resulting in a range of primary alcohols. On the other hand, the "Ru-amido state" is active for the acceptorless dehydrogenation of alcohols to yield carboxylate salts or ketones.
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