An unprecedented three-component coupling involving arynes, allyl bromides, and CO2 is described, providing efficient and facile access to structurally diverse ortho-brominated aryl esters. Unlike the conventional role played in organic synthesis as electrophiles, organic bromides served as nucleophiles in this reaction, affording a new approach to multicomponent reactions (MCRs) involving aryne intermediates. Additionally, Hammett analysis suggests that two reaction mechanisms exist, depending on the electronic nature of the cinnamyl bromides used.
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http://dx.doi.org/10.1039/c9cc05495b | DOI Listing |
Org Lett
October 2024
State Key Laboratory of Southwestern Chinese Medicine Resources, Hospital of Chengdu University of Traditional Chinese Medicine, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, P.R. China.
The (3 + 2) cycloaddition of arynes with allylic ylides remains a formidable challenge because both intermediates are highly reactive and prone to spontaneous quenching. Here, we report a (3 + 2) cycloaddition of pyrazolone MBH carbonates with arynes, enabling the efficient synthesis of diverse indene-fused spiropyrazolones. The key is employing a new bifunctional Lewis base catalyst to facilitate the cycloaddition of generated allylic pyridinium ylides with arynes.
View Article and Find Full Text PDFJ Org Chem
October 2024
Division of Organic Chemistry, CSIR-National Chemical Laboratory, Dr. Homi Bhabha Road, Pune 411 008, India.
The construction of an unprecedented tetracyclic benzoxazolo-indol-3-one scaffold has been executed through the [3 + 2]-cycloaddition of isatogens with arynes. The initially formed benzisoxazolo-indol-3-one intermediate undergoes a skeletal reorganization through a 1,3-sigmatropic shift/retro-Mannich reaction with the net formation of one C-N and two C-O bonds. The Lewis acid-catalyzed allylation of some of the resulting benzoxazolo-indol-3-ones resulted in oxazepino-indolones with promising photophysical properties.
View Article and Find Full Text PDFJ Am Chem Soc
February 2021
School of Chemistry and Chemical Engineering, Chongqing University, 174 Shazheng Street, Chongqing, P. R. China, 400030.
Although benzyne has been well-known to serve as a synthon that can conveniently prepare various 1,2-difunctionalized benzenes, the sites other than its formal triple bond remain silent in typical benzyne transformations. An unprecedented aryne 1,2,3,5-tetrasubstitution was realized from 3-silylbenzyne and aryl allyl sulfoxide, the mechanistic pathway of which includes a regioselective aryne insertion into the S═O bond, a [3,6]-sigmatropic rearrangement, and a thermal aromatic 1,3-silyl migration cascade.
View Article and Find Full Text PDFOrg Biomol Chem
April 2020
Applied Organic Chemistry Group, Chemical Science and Technology Division, CSIR-North East Institute of Science and Technology, Jorhat 785006, Assam, India. and Academy of Scientific and Innovative Research (AcSIR), CSIR-NEIST Campus, India.
A synthetic strategy has been developed for the direct synthesis of ortho-methylthio allyl and vinyl ethers via three-component reaction of in situ generated aryne, activated alkene and DMSO. This reaction proceeds via several bond cleavage and bond formation processes in a single operation. Mechanistic studies reveal that DMSO served as both a methylthiolating agent and an oxygen source.
View Article and Find Full Text PDFAcc Chem Res
February 2020
School of Chemistry and Chemical Engineering , Chongqing University, 174 Shazheng Street , Chongqing , P. R. China 400030.
Polysubstituted arenes are prevalent in numerous natural products, medicines, agrochemicals, and organic functional materials. Among methods to prepare polysubstituted arenes, pathways involving benzyne intermediates are particularly attractive given they can readily assemble highly diverse vicinal difunctionalized benzenes in a step-economical manner under transition-metal-free conditions. In order to incorporate more than two substituents on a benzene ring via a benzyne intermediate, methodologies involving benzdiyne and benztriyne have been developed, which significantly expand the current difunctionalization strategies in benzyne chemistry.
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