Visible-Light-Driven Photocatalyst- and Additive-Free Cross-Coupling of β-Ketothioamides with α-Diazo 1,3-Diketones: Access to Highly Functionalized Thiazolines |
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Authors: | Monish Arbaz Ansari Dhananjay Yadav Prof Maya Shankar Singh |
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Institution: | Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, 221005 India |
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Abstract: | A photocatalyst- and additive-free, visible-light-mediated chemoselective domino protocol was devised to access fully substituted thiazoline derivatives from β-ketothioamides and α-diazo 1,3-diketones at moderate temperature in open air. The reaction proceeds through in situ generation of electrophilic carbenes from α-diazo 1,3-diketones by a low-energy blue LED (448 nm), which undergoes selective coupling with nucleophilic β-ketothioamides to give thiazolines by successive formation of C−S and C−N bonds in one stretch. Notably, the benign and clean conditions, operational simplicity, sustainability, 100 % carbon economy, high yields, and wide functional-group tolerance are further attributes of the strategy. A mechanistic rationale for this cascade reaction sequence is well supported by control experiments. |
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Keywords: | cross-coupling cyclization heterocycles photochemistry synthetic methods |
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