High-Pressure Metal-Free Catalyzed One-Pot Two-Component Synthetic Approach for New 5-Arylazopyrazolo[3,4-b]Pyridine Derivatives

Abstract

An appropriate and efficient Q-tube-assisted ammonium acetate-mediated protocol for the assembly of the hitherto unreported 5-arylazopyrazolo[3,4-b]pyridines was demonstrated. This methodology comprises the cyclocondensation reaction of 5-amino-2-phenyl-4H-pyrazol-3-one with an assortment of arylhydrazonals in an NH4OAc/AcOH buffer solution operating a Q-tube reactor. This versatile protocol exhibited several outstanding merits: easy work-up, mild conditions, scalability, broad substrate scope, safety (the Q-tube kit is simply for pressing and sealing), and a high atom economy. Consequently, performing such reactions under elevated pressures and utilizing the Q-tube reactor seemed preferable for achieving the required products in comparison to the conventional conditions. Diverse spectroscopic methods and X-ray single-crystal techniques were applied to confirm the proposed structure of the targeted compounds.

The Q-Tube-Assisted Green Sustainable Synthesis of Fused Azines: New Synthetic Opportunities via Innovative Green Technology

“…Bearing in mind all of the above and inspired by our previous work utilizing green chemistry tools for the synthesis of biologically active heterocyclic compounds [17][18][19][20] and the recently published work on utilizing the high-pressure Q-tube [21][22][23][24][25], we are boiling point is exceeded during the reaction process. The Arrhenius equation states that reaction rates double when the temperature is raised by 10 °C (Equation (1)).…”

“…Bearing in mind all of the above and inspired by our previous work utilizing green chemistry tools for the synthesis of biologically active heterocyclic compounds [17][18][19][20] and the recently published work on utilizing the high-pressure Q-tube [21][22][23][24][25], we are On the other hand, for a plethora of organic reactions, layered double hydroxides [LDHs] can serve as catalysts [12][13][14][15]. The hydroxyl groups in Mg(OH) 2 [brucite] coordinate octahedrally with some Mg 2+ cations, similar to that in brucite, whereas some Al 3+ ions are substituted with trivalent ions.…”

“…Bearing in mind all of the above and inspired by our previous work utilizing green chemistry tools for the synthesis of biologically active heterocyclic compounds [17][18][19][20] and the recently published work on utilizing the high-pressure Q-tube [21][22][23][24][25], we are encouraged to highlight and confirm the success of the Q-tube system in organic synthesis as economic tools that save energy. In this study, we tested the Q-tube for the reaction of chalcones with nitrogen nucleophils.…”