Synthesis and <i>in vitro</i> antimicrobial evaluation of 5-amino-7-aryl-6-cyano-4<i>H</i>- pyrano[3,2,<i>b</i>]pyrrole derivatives catalyzed by reusable ZrOCl₂•8H₂O

Abstract

ABSTRACT. An efficient synthesis of a new series of 5-amino-7-aryl-6-cyano-4H-pyrano[3,2-b]pyrrole derivatives from the reaction of 3-hydroxypyrrole, malononitrile, and various aromatic aldehydes using ZrOCl2·8H2O, an environmentally friendly catalyst under a thermal solvent-free green procedure is described. This simple protocol offer advantages such as shorter reaction times, simple work-up and excellent yield. The catalyst ZrOCl2·8H2O can be reused. The reusability of the catalyst has been studied for the synthesis of 5-amino-7-aryl-6-cyano-4H-pyrano[3,2-b]pyrrole. All the compounds were screened for their antibacterial and antifungal activity.

A Greener and Rapid Approach for Synthesis of Pyranopyrroles using Nano ZnO as an efficient Catalyst

“…It is observed that with other catalysts and particularly under reflux conditions the reaction times are very much higher. Under reflux conditions, synthesis of 5-amino-7-aryl-6-cyano-4H-pyrano[3,2-b]pyrrole derivatives catalyzed by (MTSA) [18], ZrOCl 2 ·8H 2 O [22] have been reported shorter reaction times, the present method offers a comparatively very low cost and easily producible nano Zinc Oxide for effective results. (Table 3)…”

“…As a consequence of this requirement, phases that have a low stability in bulk materials can become very stable in nanostructures. In the recent years, Pyranopyrrole derivatives have been reported by using various catalysts, such as melamine trisulfonic acid (MTSA) [18], Fe(HSO 4 ) 3 [19], Zirconium(IV) dichloride [20], [pmim]HSO 4 -SiO 2 [21], ZrOCl 2 ·8H 2 O [22]. However, these methods suffer from drawbacks, such as low yields of products, tedious workup procedures, the requirement of longer reaction time and high temperature.…”