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Updated: Jul 24, 2025
Metal-free Synthesis of Ynones from Acyl Chlorides and Potassium Alkynyltrifluoroborate Salts
Published on: February 24, 2015
Chemodivergent Chalcogenation of Aryl Alkynoates or N-Arylpropynamides Using 9-Mesityl-10-Methylacridinium
Ashis Mathuri1, Buddhadeb Pal1, Milan Pramanik1
1School of Chemical Sciences, National Institute of Science Education and Research (NISER) Bhubaneswar, An OCC of Homi Bhabha National Institute, PO Bhimpur-Padanpur, Via Jatni, District Khurda, Odisha 752050, India.
Abstract:
Herein we report a cascaded chalcogenation of aryl alkynoates or N-arylpropynamides using 9-mesityl-10-methylacridinium perchlorate as a visible light photocatalyst to obtain selectively either 3-sulfenylated/selenylated coumarins or spiro[4,5]trienones. In a radical initiated process, the spiro-cyclization reaction was favored due to the presence of a -OMe or -F substituent at the para position of the aryl group, which helped to stabilize the allylic radical intermediate formed during the reaction. Otherwise, 6-endo-trig cyclization led to 3-sulfenylated/selenylated coumarins. Overall, the new C-S/C-Se, C-C, and C═O bonds were formed in a single step. The Stern-Volmer quenching study, EPR experiments, light ON-OFF experiments, radical trapping experiments, etc., helped to understand the radical-based mechanism.
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