Melamine trisulfonic acid: A new, efficient and reusable catalyst for the synthesis of some fused pyranopyrrole derivatives

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.…”

Melamine trisulfonic acid (MTSA): an efficient and recyclable heterogeneous catalyst in green organic synthesis

“…51 An environmentally friendly preparation of 5-amino-7-aryl-6-cyano-4H-pyrano[3,2-b]pyrroles via three component synthesis of malononitrile, 3-hydroxypyrrole and several aromatic aldehydes in the presence of melamine trisulfonic acid (MTSA), which was discovered by the Mansoor's group (Scheme 3). 52 The authors have screened various solvents such as ethanol, benzene, acetonitrile, methanol, cyclohexane, toluene, dichloroethane as well as solvent-free conditions in this synthesis. However, solvent-free condition was proved to be the best for this transformation.…”

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

“…However, only few reports are available for the synthesis of 5-amino-7-aryl-6-cyano-4H-pyrano [3,2-b]pyrrole derivatives [20][21][22][23][24]. In recent years, the synthesis of various 5-amino-7-aryl-6-cyano-4H-pyrano [3,2-b]pyrrole derivatives have been reported by using various promoting agents, such as ferric hydrogensulfate, Fe(HSO 4 ) 3 [20], 1-methyl-3-(triethoxysilylpropyl)-imidazolium hydrogen sulfate anchored on silica support [pmim]HSO 4 (1-propyl-3-methylimidazolium-HSO 4 ) [21], bis[N- (3,5-dicumylsalicylidene)anthracylaminato]zirconium(IV) dichloride as catalyst in the presence of ultrasonic irradiation [22] and melamine trisulfonic acid (MTSA) catalyst under solvent-free conditions [23]. Many of these methods however, suffer from drawbacks, such as low yields of products, the requirement of longer reaction time and high temperature.…”