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2000
Volume 22, Issue 5
  • ISSN: 1570-1794
  • E-ISSN: 1875-6271

Abstract

Aims and Objectives

It is well established that 4-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 4-pyran derivatives, achieved through a 1,4-Michael addition followed by a cascade cyclization. This reaction is catalyzed by LiOH·HO under ultrasonic irradiation in water, offering an efficient and environmentally friendly approach.

Materials and Methods

In this study, lithium hydroxide monohydrate (LiOH·HO) 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 involves 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 4-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.

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 4-pyrans.

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Ultrasound-assisted and Efficient Multicomponent Synthesis of 4H-Pyran Derivatives Catalyzed by LiOH.H2O in Water
Curr. Org. Synth. 22, 649 (2025); https://doi.org/10.2174/0115701794351667241112071850
/content/journals/cos/10.2174/0115701794351667241112071850
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  • Article Type:     Research Article
Keyword(s): 4H-pyrans; cyclocondensation; LiOH·H2O; multi-components; ultrasound; water

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