Photoinduced Regioselective Chalcogenation and Thiocyanation of 4H-Pyrido[1,2-a] pyrimidin-4-ones Under Benign Conditions |
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Authors: | Abhinay S. Chillal Rajesh T. Bhawale Dr. Umesh A. Kshirsagar |
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Affiliation: | Department of Chemistry, Indian Institute of Technology Indore, Khandwa Road, 453552 Indore, India |
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Abstract: | A lenient approach for regioselective C3−H chalcogenation and thiocyanation of 4H-pyrido[1,2-a] pyrimidin-4-ones is developed using visible light photocatalysis. This operationally straightforward method furnishes a broad array of C-3, Ar−S/Ar−Se and -SCN functionalized derivatives in moderate to high yields. This protocol employs visible light as an environmentally friendly energy source, cost effective inorganic persulfate-based oxidant and easily procurable dichalcogenides for regioselective C−H chalcogenation of the substrate at room temperature. Further, regioselective thiocyanation of 4H-pyrido[1,2-a] pyrimidin-4-ones was also developed. Mechanistic path for these transformations has been proposed based on light on/off and Stern-Volmer studies as well as quantum yield calculations. |
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Keywords: | C−H Functionalization Photocatalysis Pyrido[1,2-a] pyrimidin-4-ones Regioselective Visible light |
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