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Herein, we report a metal-free, N-chlorosuccinamide (NCS)-mediated, highly efficient, and regioselective C-H thio- and selenocyanation of pyrazolo[1,5-a]pyrimidines using KSCN and KSeCN respectively. The transformation required only NCS (1 equiv) and operated under mild conditions such as ambient temperature and aerobic atmosphere. This method was found to be highly efficient for the C-H thiocyanation of pyrazolo[1,5-a]pyrimidines as compared to our previously developed photocatalytic strategy and also enabled the C-H selenocyanation of the substrates to access 3-selenocyanatopyrazolo[1,5-a]pyrimidines, for the first time, which was unexplored or unsuccessful so far. A wide variety of new pyrazolo[1,5-a]pyrimidines bearing -SCN or -SeCN functional groups were synthesized in good to excellent yield. The developed protocol features a broad substrate scope, high functional group tolerance, mild conditions, high to excellent yield of products, efficient scalability, and synthetic diversifications of products. Mechanistic studies revealed an ionic pathway for this reaction.
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http://dx.doi.org/10.1002/asia.202401610 | DOI Listing |
Org Biomol Chem
September 2025
Department of Chemistry, Indian Institute of Engineering Science and Technology (IIEST), Shibpur, P O- Botanic Garden, Howrah- 711103 (WB), India.
A simple yet efficient method involving a visible-light-induced direct, regioselective chalcogenation of indoloquinoxaline derivatives has been developed. Thiols, disulfides and diselenides were found to be efficient as chalcogenating agents in the presence of Rose Bengal as a photosensitizer. This photoinduced C-H functionalization a cross-dehydrogenative-coupling (CDC) protocol was carried out at ambient temperature under an open-air atmosphere.
View Article and Find Full Text PDFChem Commun (Camb)
September 2025
Center for Drug Research and Development, Guangdong Pharmaceutical University, Guangzhou, 510006, P. R. China.
Herein, we report an Ir(III)-catalyzed regioselective C-H acylmethylation of indolizines with β-ketosulfoxonium ylides, enabling the efficient synthesis of C3-functionalized indolizine derivatives. By modifying the reaction conditions, a controllable Ir(III)-catalyzed dicarbonylation of the same substrates was also achieved. In this transformation, β-ketosulfoxonium ylides serve as a rare alternative to conventional oxophenacyl halides.
View Article and Find Full Text PDFChem Sci
August 2025
College of Chemistry and Chemical Engineering, Jiangxi Province Engineering Research Center of Ecological Chemical Industry, Jiujiang University Jiujiang 332005 China
BN-fused aromatic compounds have garnered significant attention due to their unique electronic structures and exceptional photophysical properties, positioning them as highly promising candidates for applications in organic optoelectronics. However, the regioselective synthesis of BN isomers remains a formidable challenge, primarily stemming from the difficulty in precisely controlling reaction sites, limiting structural diversity and property tunability. Herein, we propose a regioselective synthetic strategy that employs 2,1-BN-naphthalene derivatives, wherein selective activation of N-H and C-H bonds is achieved in conjunction with -halogenated phenylboronic acids.
View Article and Find Full Text PDFJ Org Chem
September 2025
School of Chemistry and Chemical Engineering, Huaibei Normal University, Huaibei, Anhui 235000, P. R. China.
Radical cascade cyclization of alkenes involving the insertion of sulfur dioxide has proven to be a promising tool to access sulfonylnated heterocycle compounds, whereas cyclization of unactivated alkenes has been much less explored. Here, we developed a three-component cascade of unactive alkenes with sulfur dioxide and aryldiazonium tetrafluoroborates to generate sulfonylated tetrahydropyridines and azepines via the cleavage of alkenyl C-H bonds. Moreover, this protocol exhibited excellent chemical and regioselectivity and compatibility with broad functional groups.
View Article and Find Full Text PDFJ Org Chem
August 2025
Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan.
Transformation of allylic C-H bonds into C-C bonds in a regioselective manner represents a powerful approach to generating complex molecules from simple starting materials. Herein, we report a protocol for net δ-C-H alkylation of allyl alcohols involving a sequential azo-ene reaction and an attendant Ni-catalyzed allylic substitution with Grignard reagents. This two-step strategy enables the regioselective alkylation of distal C-H bonds, a transformation that remains challenging via direct approaches under transition-metal catalysis.
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