N-Benzyl-2-nitrobenzenesulfonamides underwent base-mediated intramolecular arylation at the benzyl sp(3) carbon to yield benzhydrylamines. The presence of electron withdrawing groups on the aromatic ring of the benzyl group was required to facilitate the C-arylation. Unsymmetrically substituted benzhydrylamines are advanced intermediates toward nitrogenous heterocycles, as exemplified in the syntheses of indazole oxides and quinazolines.
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http://dx.doi.org/10.1021/co500098y | DOI Listing |
RSC Adv
November 2024
Department of Organic Synthesis and Process Chemistry, CSIR-Indian Institute of Chemical Technology (CSIR-IICT) Hyderabad 500 007 India
This study presents the design and application of intramolecular arylogous nitroaldol (Henry) condensation. A transition metal-free, base-mediated reaction of -heteroatom-substituted aryl aldehydes/ketones and 2-nitrobenzyl (pseudo)halides has been developed to access a wide range of 2-(2-nitroaryl)benzofuran/2-(2-nitroaryl)indole derivatives in high yields. The reaction appears to proceed through -/-benzylation and intramolecular arylogous nitroaldol condensation.
View Article and Find Full Text PDFOrg Lett
September 2024
State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources, College of Chemistry, Xinjiang University, Urumqi 830046, Xinjiang, P. R. China.
A base-mediated regioselective [3 + 3] annulation of alkylidene malononitriles with trifluoromethyl alkenes was described. The reaction proceeds through sequential intermolecular S2' and intramolecular SV-type cyclization by cleaving dual C-F bonds in a trifluoromethyl group, which discriminate multiple carbon-nucleophilic sites using a single base. Various bicycles bearing a monofluorocyclohexene motif were assembled from readily available starting materials under mild conditions via a one-pot cascade approach.
View Article and Find Full Text PDFJ Org Chem
September 2024
Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China.
Decarboxylative C(sp2)-heteroatom cross-coupling reactions hold extraordinary potential for the sustainable preparation of biologically active scaffolds. Herein, we report a copper sulfate/1,10-phenathroline catalytic system for the decarboxylative intramolecular C(sp2)-O, C(sp2)-S, and C(sp2)-N coupling reactions leading to the construction of a series of benzo[]furans, benzo[]thiophenes, and indole derivatives from the corresponding coumarins, thiocoumarins, or quinolones, respectively. Our mechanistic study based on benzo[]furan formation suggests a three-step process of the transformations, which consists of (i) base-mediated hydrolytic ring opening of coumarin, (ii) copper-oxygen co-initiated radical decarboxylation, and (iii) copper-catalyzed C-heteroatom cross coupling.
View Article and Find Full Text PDFJ Am Chem Soc
September 2024
Max-Planck-Institut für Kohlenforschung, 45470 Mülheim/Ruhr, Germany.
It was recognized only recently that the sister norcembranoids scabrolides A and B have notably different carbotricyclic scaffolds. Therefore, our synthesis route leading to scabrolide A could not be extended to its sibling. Rather, a conceptually new approach had to be devised that relied on a challenging intramolecular alkenylation of a ketone to forge the congested central cycloheptene ring at the bridgehead enone site; the required cyclization precursor was attained by a lanthanide-catalyzed Mukaiyama-Michael addition.
View Article and Find Full Text PDFJ Org Chem
August 2024
Department of Pharmaceutical Technology (Process Chemistry), National Institute of Pharmaceutical Education and Research, S. A. S. Nagar, Punjab 160062, India.
A reductive amidation of unactivated esters with nitroarenes, a key step in the telescopic synthesis of tetrahydropyrrolo[1,2-]quinoxalinones and tetrahydropyrido[1,2-]quinoxalinones, is reported. The process involves an intermolecular base-mediated SAr reaction, followed by intramolecular reductive amidation employing sodium dithionite. The substrate scope coupled with the demonstration of the synthesis of pharmaceuticals is reported.
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