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BF3·OEt2-Mediated Tandem Annulation: A Strategy To Construct Functionalized Chromeno- and Pyrano-Fused Pyridines
K T Ashitha1,2, V Praveen Kumar1,2, C T Fathimath Salfeena1,2
1Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST) , Thiruvananthapuram 695 019, India.
Abstract:
A simple and efficient one-pot annulation of arylidenones, alkynes, and nitriles in the presence of BF3·OEt2 is described. A highly functionalized variety of N-substituted pyridine-fused chromeno and pyrano derivatives were obtained with satisfactory yields under mild reaction conditions. The method was proven to be valid for the synthesis of a diverse library of chromeno[3,4-c]pyridines, thiochromeno[3,4-c]pyridines, pyrano[3,4-c]pyridines, and thiopyrano[3,4-c]pyridine derivatives from readily accessible substrates. This experimentally simple protocol provides structurally complex, biologically relevant heterocycles in a one-pot operation.
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