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L-Cysteine catalyzed environmentally benign one-pot multicomponent approach towards the synthesis of dihydropyrano[2,3-c]pyrazole derivatives.
Current Organic Synthesis ( IF 1.8 ) Pub Date : 2020-08-31 , DOI: 10.2174/1570179417666200511092332
Sana Sikandar 1 , Ameer Fawad Zahoor 1 , Sajjad Ahmad 2 , Muhammad Naveed Anjum 3 , Mirza Nadeem Ahmad 3 , Muhammad Sami Ullah Shah 1
Affiliation  

Background: The pyrano[2,3-c]pyrazole derivatives are important building blocks of many biologically active compounds owing to their diverse biological potential for example, anti-inflammatory, anticancer, anti-microbial and anti-oxidant properties.

Objective: Keeping in mind the wide range of applications of pyrano[2,3-c]pyrazoles, herein we intended to develop a novel synthetic methodology for dihydropyranopyrazoles. We were also interested in determining the influence of amino acids and dipeptides as a catalyst on the synthesis of pyrano[2,3-c]pyrazole derivatives.

Methods: To achieve our objectives, we used a one-pot multi-component reaction of ethyl 3-oxobutanoate, propanedinitrile, hydrazine monohydrate and several substituted benzaldehydes by using different catalysts and solvents to synthesize our desired products in the presence of various catalysts.

Results and Discussion: We found that optimal conditions for the preparation of pyrano[2,3-c]pyrazoles were L-cysteine (0.5 mol) in the presence of water:ethanol (9:1) at 90 °C. Various 1,4-dihydropyrano[2,3- c]pyrazoles were afforded by using several substituted benzaldehydes in 66-97% yields.

Conclusion: We described a green and environmentally benign method to synthesize pyrano[2,3-c]pyrazoles in a one-pot four component reaction of ethyl 3-oxobutanoate, propanedinitrile, hydrazine monohydrate and different substituted benzaldehyde in the presence of L-cysteine in aqueous ethanol (9:1) at 90 oC. Excellent yields of the products, simple work-up, easily available starting materials, use of green solvents, naturally occurring catalyst, non-toxicity, non-chromatographic purification and environmentally benign reaction conditions are some main advantages of this protocol.



中文翻译:

L-半胱氨酸催化环境友好的一锅多组分方法合成二氢吡喃并[2,3-c]吡唑衍生物。

背景:吡喃并[2,3-c]吡唑衍生物由于具有多种生物潜力,例如抗炎,抗癌,抗微生物和抗氧化特性,是许多生物活性化合物的重要组成部分。

目的:牢记吡喃并[2,3-c]吡唑的广泛应用,在此我们打算开发一种新颖的二氢吡喃并吡咯合成方法。我们也有兴趣确定氨基酸和二肽作为催化剂对吡喃并[2,3-c]吡唑衍生物合成的影响。

方法:为了实现我们的目标,我们使用了3-氧化丁酸乙酯,丙二腈,一水合肼和几种取代的苯甲醛的单锅多组分反应,方法是在各种催化剂存在下,使用不同的催化剂和溶剂合成所需的产物。

结果与讨论:我们发现制备吡喃并[2,3-c]吡唑的最佳条件是在90°C的水:乙醇(9:1)存在下L-半胱氨酸(0.5 mol)。通过使用几种取代的苯甲醛以66-97%的产率提供各种1,4-二氢吡喃并[2,3-c]吡唑。

结论:我们描述了一种绿色环保的方法,可在L-半胱氨酸存在的情况下,通过3-氧代丁酸乙酯,丙腈,一水合肼和不同取代的苯甲醛的一锅四组分反应合成吡喃并[2,3-c]吡唑在90°C的乙醇水溶液(9:1)中溶解。该方案的主要优点是产品的产率高,后处理简单,原料易得,绿色溶剂的使用,天然催化剂,无毒,无色谱纯化和环境友好的反应条件。

更新日期:2020-09-25
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