Recyclable [RuCl2(p-cymene)]2/PEG-400/H2O System for Efficient Annulation of N-Methoxybenzamides with Alkynes Under External Oxidant-Free Conditions

[RuCl 2 ( p -cymene)] 2 in a mixture of poly(ethylene glycol) (PEG-400) and water is shown to be a highly efficient catalyst for the annulation of N -methoxybenzamides with alkynes. The reaction proceeded smoothly at 60 ºC with MesCO 2 K as a cocatalytic additive under external oxidant-free conditions, delivering a variety of substituted isoquinolones in mostly good to excellent yields. The isolation of the crude products can be easily performed by extraction with diethyl ether and more importantly, [RuCl 2 ( p -cymene)] 2 /PEG-400/H 2 O system could be facilely recycled and reused more than six times without any apparent loss of catalytic efficiency. Graphical Abstract Ruthenium-catalyzed annulation of N -methoxybenzamides with alkynes leading to isoquinolones by using [RuCl 2 (p-cymene)] 2 /PEG-400/H 2 O as a highly efficient and recyclable catalytic system is described.