Synthesis of substituted isoquinolines via iminoalkyne cyclization using Ag(i) exchanged K10-montmorillonite clay as a reusable catalyst

Abstract

Monosubstituted isoquinolines are synthesized in good to excellent yields by the Ag(I)-exchanged K10-montmorillonite clay catalyzed ring closure of iminoalkynes. This silver catalyzed ring closure is highly effective in cyclizing aryl- and alkyl-substituted iminoalkynes at 100 °C and accommodates a variety of iminoalkynes, thus affording a convenient route to the synthesis of isoquinolines. The other salient features of this procedure are its reusability, environmentally benign nature, high yield, operational simplicity with fewer steps, easy separation, and minimization of metallic wastes. The reaction proceeds smoothly in moderate yields and tolerates various functional groups. The solid catalyst can be readily recovered and reused. Notably, no additional base or other co-catalysts are needed. A plausible mechanism is proposed in which isoquinolines are formed via simultaneous bifunctional acid-base catalysis by Ag(I) clay.