A convenient synthesis of quinoline fused triazolo-azepine/oxepine derivatives through Pd-catalyzed C-H functionalisation of triazoles
An efficient and convenient synthesis of new fused heterocyclic scaffold comprising three different heterocycles viz. quinoline,azepine/oxepine and triazoleis reported from quinoline tethered triazoles. The quinoline tethered triazoles were easily obtained in three steps from 2-chloro-3-formylquinolines,that is, reductive amination with benzyl amines, N-propargylation followed by ‘click’ reaction under standard conditions. For the first time, we present quinoline fused triazolo-azepines in good to high yields by palladium-catalysed C-H functionalisation at C-5position of triazole moiety. The protocol readily extended even to the construction of quinoline fused triazolo-oxepines from (2-chloroquinolin-3-yl)methanol through the similar sequence,that is, O-propargylation,click reaction and palladium catalysedC-H functionalisation.