Current Organic Synthesis - Volume 18, Issue 2, 2021

In this review, authors focus mostly on the various synthetic strategies developed so far for 1,2,3- triazole scaffold and its derivatives via different approaches such as metal-free, metal assisted or bimetallic. A brief overview of applications of the very important 1,2,3-triazole scaffold along with pharmacological activity is also discussed. Synthetic strategies are updated until June 2020.

Dess–Martin periodinane (DMP), a commercially available chemical, is frequently utilized as a mild oxidative agent for the selective oxidation of primary and secondary alcohols to their corresponding aldehydes and ketones, respectively. DMP shows several merits over other common oxidative agents such as chromiumand DMSO-based oxidants; thus, it is habitually employed in the total synthesis of natural products. In this review, we try to underscore the applications of DMP as an effective oxidant in an appropriate step (steps) in the multi-step total synthesis of natural products.

Pyrazole and its derivatives have gained wide attention in pharmaceutical, agrochemical and biological fields as well as in industry. They exhibit various biological activities such as anti-pyretic, anti-microbial, anti- inflammatory, anti-tumor, anti-viral, anti-histaminic, anti-convulsant, fungicidal, insecticidal, etc. In this review, we summarise the recent advances in the synthesis of pyrazole derivatives using various methodologies and covers literature from 2017-2020.

Aims and Objective: Synthesis of novel bis-spirooxindoles was carried out from isatins, two equivalents of malononitrile, and various derivatives of cyclohexanones. Background: A facile one-pot and four-component reaction was investigated for the synthesis of novel bisspirooxindoles from different derivatives of isatins, two equivalents of malononitrile and various derivatives of cyclohexanone in the presence of magnetic CoFe2O4@MCM-41@MgO NPS catalyst under mild conditions. Materials and Methods: Firstly, the magnetic CoFe2O4@MCM-41@MgO was prepared in three steps. Afterwards, the CoFe2O4@MCM-41@MgO was used as a base catalyst for the one-pot synthesis of bisspirooxindoles. Results and Discussion: The procedure exhibited several benefits, an excellent yield of products, short reaction times, reusability, and recyclability of the nanocatalyst. Conclusion: The structure of nanocatalyst was recognized by FT-IR, XRD, VSM, SEM, BET, and EDX techniques, and the structure of the organic products was determined by melting point, FT-IR, 1H NMR, 13C NMR, Mass spectra, and C.H.N analyses.

Aims: In this article, we have developed an eco-friendly one-pot multi-component reaction methodology employed for the green synthesis of functionalized pyrazole derivatives viz cyclo-condensation of aromatic aldehydes, ethyl acetoacetate and phenyl hydrazine and/or hydrazine hydrate in the presence of cetyltrimethylammoniumbromide (CTAB) at 90°C temperature in an aqueous medium. Materials and Methods: In the present protocol, we developed a green method for the synthesis of functionalized pyrazole derivatives through one-pot, multi-component cyclo-condensation of aromatic aldehydes, phenyl hydrazine or hydrazine hydrate and ethyl acetoacetate using cetyltrimethylammoniumbromide (CTAB) as a catalyst in water as a solvent. Our methodology confers advantages such as short reaction time, atom economy, purification of the product without using column chromatographic and hazardous solvent. The reaction is being catalyzed by cetyltrimethylammoniumbromide (CTAB) and thus, products are formed under the green reaction conditions. Results and Discussion: Initially, the reaction of benzaldehyde and phenylhydrazine with ethyl acetoacetate was carried out in water at room temperature in the absence of the catalyst; no product was obtained after 24 h. When the reaction was carried out using L-proline as a catalyst in ethanol at 70°C, the yield of the product was 20%. Conclusion: This research not only provides a green and efficient method for the synthesis of sulfinic esters but also shows new applications of electrochemistry in organic synthesis. We consider that this green and efficient synthetic protocol used to prepare sulfinic esters will have good applications in the future. In conclusion, we have developed successfully a green and efficient one-pot multi-component methodology for the synthesis of substituted pyrazoles using CTAB as a catalyst in water as a solvent with excellent yields. Purifications of compounds were achieved without the use of traditional chromatographic procedures. This methodology has advantages of operational simplicity, clean reaction profiles and relatively broad scope, which make it more attractive for the diversity oriented synthesis of these heterocyclic libraries. In this methodology, we suggest a further alternative possibility for the formation of substituted pyrazoles. The compound 7h can be used as an anticancer drug in the pharma industry.