A novel pattern of the cleavage and reorganization of C=N bond in the multicomponent reaction (MCR) of terminal alkynes or haloalkynes, carbodiimides, and benzynes is achieved for the first time to construct efficiently 2-aminoaryl alkynyl imines. The selective formation and ring-opening of the azetine intermediate with the high ring strain is essential for this reaction. Further transformation of 2-aminoaryl alkynyl imines via the Cu-catalyzed cycloisomerization is explored to provide steroselectively the bi-, tri-, and tetracyclic fused pyrrolines.
Keywords: CN activation; alkynes; benzynes; carbodiimides; multicomponent reactions.
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