A high efficiency protocol was developed for the synthesis of 2,5-disubstituted oxazoles via iodine-promoted oxidative domino cyclization. These reactions were performed with readily available methyl azaarenes and α-amino ketones under metal-free conditions. This protocol is a simple method with high functional group compatibility, a wide range of substrates, and excellent yield, providing a new way to synthesize azaarene-attached oxazoles.
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http://dx.doi.org/10.1021/acs.joc.2c01399 | DOI Listing |
Org Biomol Chem
August 2024
Organic Synthesis & Catalysis Lab, Department of Chemistry, National Institute of Technology Warangal, Hanumakonda - 506004, Telangana, India.
An I-promoted, metal-free protocol has been developed for the one-pot synthesis of 6-aroyl-5,6-dihydro-8-quinazolino[4,3-]quinazolin-8-ones from readily accessible substrates. This reaction involves the sp C-H oxidation of aryl methyl ketones to phenylglyoxal, followed by imine formation and intramolecular nucleophilic addition, resulting in the formation of two new C-N bonds. Furthermore, the method is applicable to a wide range of aryl methyl ketones, including heterocycles and drug-derived substrates, yielding the desired products with yields ranging from 62% to 93%.
View Article and Find Full Text PDFJ Org Chem
August 2024
Department of Chemistry, Handique Girls' College, Guwahati 781001, Assam, India.
An iodine-promoted C═C bond cleavage with concomitant decarboxylation and cross-coupling between cinnamic acids and -sulfoximines has been developed. This reaction proceeds via selective C═C bond cleavage, followed by decarboxylation and oxidative sulfoximidation. This metal- and base-free protocol involves dioxygen as the source of oxygen, which is facilitated by -butyl hydroperoxide (TBHP) as the oxidant affording -aroylated sulfoximines with good functional group tolerance and good yields.
View Article and Find Full Text PDFRSC Adv
May 2024
Faculty of Chemical Engineering, Ho Chi Minh City University of Technology 268 Ly Thuong Kiet, District 10 Ho Chi Minh City Vietnam
A highly efficient method for the direct construction of amide bonds a selective cleavage of C-H and C[double bond, length as m-dash]C bonds in indole structures using an iodine-promoted approach was developed. Mechanistic studies indicated the formation of superoxide radicals obtained from molecular oxygen activation as a key intermediate step, which provided a precursor for subsequent oxidative ring-opening and intermolecular cyclization. A broad range of quinazolin-4(3)-ones and tryptanthrins were synthesized in moderate to good yields under mild and environmentally benign conditions.
View Article and Find Full Text PDFJ Org Chem
February 2024
National Key Laboratory of Green Pesticide, International Joint Research Center for Intelligent Biosensor Technology and Health, College of Chemistry, Central China Normal University, Wuhan 430079, P. R. China.
A novel iodine-promoted difunctionalization of α-C sites in enaminones was demonstrated as a means of synthesizing a variety of fully substituted thiazoles by constructing C-C(CO), C-S, and C-N bonds. This transformation allows the realization of enaminones as unusual aryl C2 synthons and simultaneously allows the thioylation and dicarbonylation of α-C sites. A preliminary mechanistic study was performed and indicated that the cleavage of C═C bonds in enaminones involves a bicyclization/ring-opening and oxidative coupling sequence.
View Article and Find Full Text PDFOrg Lett
June 2023
Key Laboratory of Applied Surface and Colloid Chemistry & School of Chemistry and Chemical Engineering, Shaanxi Normal University, 620 West Chang'an Ave, Xi'an, 710119, China.
Herein, we report an efficient synthetic method for constructing the tetracyclic scaffold of sulfur-containing discorhabdin-type alkaloids. The key to success is the BF•EtO-promoted dienone-phenol-type rearrangement/sulfur insertion cascade reaction, which converts the common and readily available -acetal-bridged tetracyclic framework to the labile and synthetically challenging -acetal-bridged tetracyclic framework in a single step. Additionally, the hypervalent iodine promoted intramolecular oxidative dearomatization terminated with amide and indium(III) acetate-facilitated radical cyclization were also essential elements in this study.
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