A novel Brønsted acid-catalyzed oxidative C-H functionalization of alkynyl thioethers has been developed. This method allows the practical synthesis of valuable isothiochroman-3-ones in mostly moderate to good yields under mild reaction conditions and features a broad substrate scope and wide functional group tolerance. Moreover, this metal-free oxidation can also be used to promote formal N-H insertion involving an unexpected 1,2-sulfur migration, affording useful 1,4-benzothiazin-3-ones.
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http://dx.doi.org/10.1021/acs.orglett.8b03462 | DOI Listing |
Angew Chem Int Ed Engl
October 2024
Key Laboratory of Molecule Synthesis and Function Discovery, Fujian Province University, College of Chemistry at Fuzhou University, Fuzhou, Fujian, 350108, China.
Zweifel reaction is a powerful strategy to construct olefins from alkenyl tetracoordinate borons in organoboron chemistry, however, it usually only involves one functional group migration and then undergoes an elimination process affording alkenes or alkynes exclusively. Herein, we disclose several intriguing interception of alkynyl tetracoordinate borons with sulfur electrophiles. Wherein, the substituted benzothiophenes are accessed by consecutive 1,2-migrations and intramolecular electrophilic substitution, meanwhile, the challenging and elusive five/four-membered boracycles are easily assembled, and an approach to alkenyl sulfides with good stereoselectivity was developed as well.
View Article and Find Full Text PDFOrg Biomol Chem
August 2024
Department of Chemistry, Lishui University, No. 1, Xueyuan Road, Lishui City 323000, Zhejiang Province, P. R. China.
Alkynes are important in organic synthesis. This review mainly focuses on recent advances (2013-2023) on alkynes with C-S bond formation, based on more than 30 types of sulfur reagents. The reactions of alkynes with various sulfur-containing compounds including RSSR (disulfides), RSH (thiols), S (elemental sulphur), alkynyl thioethers, RSCN, AgSCF, KS, NaS, dithiane, RSCl, NFSI, RNCS, EtOCSK, thiocarbamate, RSONH, thiourea, sulfoxide, RSON, CS, RSONH, RSONHNH, RSOCl, RSOOar, RSOSR', DABCO·(SO), NaSO, KSO, RSOH, RSONa and related compounds are discussed.
View Article and Find Full Text PDFNat Commun
May 2024
Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, China.
Herein, we disclose a highly efficient cobalt-catalyzed cross-electrophile alkynylation of a broad range of unactivated chlorosilanes with alkynyl sulfides as a stable and practical alkynyl electrophiles. Strategically, employing easily synthesized alkynyl sulfides as alkynyl precursors allows access to various alkynylsilanes in good to excellent yields. Notably, this method avoids the utilization of strong bases, noble metal catalysts, high temperature and forcing reaction conditions, thus presenting apparent advantages, such as broad substrate scope (72 examples, up to 97% yield), high Csp-S chemo-selectivity and excellent functional group compatibility (Ar-X, X = Cl, Br, I, OTf, OTs).
View Article and Find Full Text PDFChemistry
July 2024
School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
The regiodivergent synthesis of 4- and 5-sulfenyl oxazoles from 1,4,2-dioxazoles and alkynyl thioethers has been achieved. Gold-catalysed conditions are used to favour the formation of 5-sulfenyl oxazoles via β-selective attack of the nitrenoid relative to the sulfenyl group. In contrast, 4-sulfenyl oxazoles are formed by α-selective reaction under Brønsted acid conditions from the same substrates.
View Article and Find Full Text PDFJ Org Chem
May 2024
State Key Laboratory of Pulp and Paper Engineering, Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510641, China.
A practical and efficient method to access polysubstituted aryl sulfides has been discovered via a Lewis acid-catalyzed reaction between alkynyl sulfide and 2-pyrone, involving a Diels-Alder/retro-Diels-Alder pathway. Alkynyl sulfide as an electron-rich dienophile and 2-pyrones as electron-poor dienes are conjunctively transformed into a series of polysubstituted aryl sulfides with broad functional group compatibility in good to excellent yields (40 examples, 43-88% yield). The robustness and practicality of the protocol has been demonstrated through gram-scale synthesis and the ease of transformation of the resulting products.
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