Abstract
A sequence of pyrano[2, 3-c]pyrazoles was constructed through promoting an eco-friendly, green, and efficient approach. M1-M25 derivatives were developed by a base-catalyzed one-pot reaction involving application of hydrazine hydrate 96%, β-keto ester as ethyl acetoacetate or diethyl malonate, aryl/heteroaryl aldehyde or isatin, and enolizable active methylene compounds with isolation of unexpected compound M2. Further on, intramolecular cyclization of compounds M10, M13 with formic acid, acetic anhydride, and formamide leads to the corresponding pyrimidine derivatives M26-M31. Afterwards, the antimicrobial activity of the compounds was evaluated and fortunately, the vast majority of the compounds showed outstanding anti-bacterial results. Besides, the potential mode of action of the synthesized compounds was determined by employing a molecular-docking study against penicillin-binding protein implicated in anti-bacterial action. Compound M21 was one of the most promising anti-bacterial agents with potential binding affinity against the penicillin-binding protein. This study shed light on novel compounds for further antimicrobial drug development.
Highlights
Synthetic organic chemists centered their attention on developing practical methods, conditions, usage of materials, and the reaction media depending on green chemistry principles.[2]
Base-catalyzed one-pot four-component approach was conducted to synthesize various 1,4dihydro-pyrano[2,3-c]pyrazole derivatives using a clean method of simple conditions to adopt the principles of green chemistry
The synthesis of 1,4-dihydro-pyrano [2,3-c]pyrazoles derivatives M1M21 in 85-93% yields could be accomplished by tandem Knoevenagel condensation/Michael addition/imine–enamine tautomerism/O-cyclization through the reaction of hydrazine hydrate, 96% 1, β-keto ester as ethyl acetoacetate or diethyl malonate 2, aryl/heteroaryl aldehyde 3, and enolizable active methylene compounds as malononitrile or ethyl cyanoacetate or diethyl malonate 4 in the
Summary
Synthetic organic chemists centered their attention on developing practical methods, conditions, usage of materials, and the reaction media depending on green chemistry principles.[2]. Multicomponent reactions (MCRs) are processes for constructing molecular diversity and complexity through a concerted reaction involving a combination of three or more reactants.[3]. The MCRs evolvement has brought about a paradigm shift in current day research in synthetic organic, medicinal, and combinatorial chemistry by complying with the green chemistry principles in terms of frugality of energy and steps and waste pot MCRs allow swift approach to combinatorial libraries of bioactive scaffolds and -lessening.[4]. MCRs offer significant features over conventionally linear-type synthesis by dint of their building up various organic molecules from pot process with inherent flexibility, selective convergence, good -obtainable reactants in a one productivity, facile execution, and high yields.[6]. The first multicomponent reaction was described in 1850 by Strecker, and subsequently, various reactions of such type have been published.[7, 8]
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