Synthesis of 5H-chromeno[3,4-c]pyridine derivatives through ruthenium-catalyzed [2 + 2 + 2] cycloaddition

Abstract

Valuable 5H-chromeno[3,4-c]pyridines were conveniently prepared through ruthenium-catalyzed [2 + 2 + 2] cycloaddition of diversely substituted α,ω-diynes with various cyanamides. The reaction was highly regioselective and tolerated a wide range of 1-ethynyl-2-(prop-2-yn-1-yloxy)benzene derivatives and cyanamides providing 32 new tricyclic pyridines that can serve as building blocks for further functionalization and enable access to a biologically relevant intermediate.