One-Pot Tandem Nickel-Catalyzed α-Vinyl Aldol Reaction and Cycloaddition Approach to [1,2,3]Triazolo[1,5- a ]quinolines.

A one-pot tandem approach to [1,2,3]triazolo[1,5- a ]quinolines was developed from ( E )-β-chlorovinyl ketones and 2-azidoaryl carbonyls using a sequence of α-vinyl aldol and azide-alkyne cycloaddition reactions. In particular, the intramolecular azide-alkyne cycloaddition of allenol intermediates was readily promoted by a synergistic action of NEt 3 and nickel catalysts. Given that the [1,2,3]triazolo[1,5- a ]quinolines are useful synthetic precursors to α-diazoimines through ring-chain isomerization process, the subsequent denitrogenative transformations should provide ready access to valuable heterocyclic compounds.