{"title":"Ultrasound-assisted and Efficient Multicomponent Synthesis of 4H-Pyran Derivatives catalyzed by LiOH.H2O in Water.","authors":"Nihel Masmoudi, Manef Chtourou","doi":"10.2174/0115701794351667241112071850","DOIUrl":null,"url":null,"abstract":"<p><strong>Aim and objective: </strong>It is well established that 4H-pyran derivatives hold a significant position in synthetic organic chemistry due to their diverse biological and pharmacological properties. This work aims to introduce a novel synthetic pathway for highly functionalized 4H-pyran derivatives, achieved through a 1,4-Michael addition followed by a cascade cyclization. This reaction is catalyzed by LiOH·H2O under ultrasonic irradiation in water, offering an efficient and environmentally friendly approach.</p><p><strong>Materials and methods: </strong>In this study, lithium hydroxide monohydrate (LiOH·H2O) was used as the catalyst. To explore environmentally friendly methods, two novel approaches utilizing pure water were investigated (Method 1 and Method 2). The first method in-volves the use of alkylidene reagents malononitrile and ethyl acetoacetate in an aqueous medium. The second method features a multi-component cyclocondensation of aromatic aldehydes, malononitrile, and ethyl acetoacetate, activated by ultrasound waves and conducted in pure water. The impact of various substituents on the formation of 4H-pyrans, including both electron-poor and electron-rich aromatic aldehydes, was also evaluated.</p><p><strong>Results: </strong>Most products were obtained in high yield and as very pure crystals with distinct colors. Generally, aromatic aldehydes with electron-withdrawing groups (Cl) exhibited greater reactivity than those with electron-donating groups (OMe). This trend is clearly demonstrated when comparing entries 3 and 4 with entries 5 and 6 in Tables 1-6.</p><p><strong>Conclusion: </strong>Compared to other procedures, this method is simple, fast, eco-compatible since it uses water as a solvent. In addition, the products are obtained in good yields in the pure state after simple recrystallization without the need for other purification techniques, such as column chromatography. These factors make this novel approach highly attractive for the synthesis of 4H-pyrans.</p>","PeriodicalId":11101,"journal":{"name":"Current organic synthesis","volume":" ","pages":""},"PeriodicalIF":1.7000,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Current organic synthesis","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.2174/0115701794351667241112071850","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
引用次数: 0
Abstract
Aim and objective: It is well established that 4H-pyran derivatives hold a significant position in synthetic organic chemistry due to their diverse biological and pharmacological properties. This work aims to introduce a novel synthetic pathway for highly functionalized 4H-pyran derivatives, achieved through a 1,4-Michael addition followed by a cascade cyclization. This reaction is catalyzed by LiOH·H2O under ultrasonic irradiation in water, offering an efficient and environmentally friendly approach.
Materials and methods: In this study, lithium hydroxide monohydrate (LiOH·H2O) was used as the catalyst. To explore environmentally friendly methods, two novel approaches utilizing pure water were investigated (Method 1 and Method 2). The first method in-volves the use of alkylidene reagents malononitrile and ethyl acetoacetate in an aqueous medium. The second method features a multi-component cyclocondensation of aromatic aldehydes, malononitrile, and ethyl acetoacetate, activated by ultrasound waves and conducted in pure water. The impact of various substituents on the formation of 4H-pyrans, including both electron-poor and electron-rich aromatic aldehydes, was also evaluated.
Results: Most products were obtained in high yield and as very pure crystals with distinct colors. Generally, aromatic aldehydes with electron-withdrawing groups (Cl) exhibited greater reactivity than those with electron-donating groups (OMe). This trend is clearly demonstrated when comparing entries 3 and 4 with entries 5 and 6 in Tables 1-6.
Conclusion: Compared to other procedures, this method is simple, fast, eco-compatible since it uses water as a solvent. In addition, the products are obtained in good yields in the pure state after simple recrystallization without the need for other purification techniques, such as column chromatography. These factors make this novel approach highly attractive for the synthesis of 4H-pyrans.
期刊介绍：
Current Organic Synthesis publishes in-depth reviews, original research articles and letter/short communications on all areas of synthetic organic chemistry i.e. asymmetric synthesis, organometallic chemistry, novel synthetic approaches to complex organic molecules, carbohydrates, polymers, protein chemistry, DNA chemistry, supramolecular chemistry, molecular recognition and new synthetic methods in organic chemistry. The frontier reviews provide the current state of knowledge in these fields and are written by experts who are internationally known for their eminent research contributions. The journal is essential reading to all synthetic organic chemists. Current Organic Synthesis should prove to be of great interest to synthetic chemists in academia and industry who wish to keep abreast with recent developments in key fields of organic synthesis.
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