Tandem Knoevenagel-Michael reactions in aqueous diethylamine medium: A greener and efficient approach toward bis-dimedone derivatives

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• 作者：Abdullah Mohammed Al-Majid^a ; ¹ ; Mohammad Shahidul Islam^a ; ¹ ; ^{shahid.10amui@gmail.com} ; Assem Barakat^a ; ^b ; ¹ ; ^{ambarakat@ksu.edu.sa} ; Nasser J. Al-Qahtani^c ; ¹ ; Sammer Yousuf^d ; ¹ ; M. Iqbal Choudhary^a ; ^d ; ¹
• 关键词：Tandem Knoevenagel&ndash ; Michael reactions ; MCRs ; Aqueous media ; Dimedone ; Zwitterions
• 刊名：Arabian Journal of Chemistry
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：10
• 期：2
• 页码：185-193
• 全文大小：909 K
• 卷排序：10

文摘

Diethylamine catalyzed tandem Knoevenagel–Michael reactions have been carried out in aqueous medium as an efficient, greener and cost effective process for the simple one-pot synthesis of bis-dimedone derivatives. Reaction of substituted aromatic aldehyde (1 equiv.) and dimedone (2 equiv.), in the presence of aqueous diethylamine medium at room temperature provides bis-dimedone derivatives 3a–n in excellent yields (87–95%) within a very short reaction time (15–60 min). All the bis-dimedone derivatives were obtained in high purity and the products were fully characterized by physical and spectroscopic data. The structures of compounds 3b,c were elucidated by single crystal X-ray diffraction technique. Compound 3b crystallizes in the monoclinic space group P 21/n with a = 10.2895(9) ÅÅ, b = 18.0995(15) ÅÅ, c = 15.8615(13) ÅÅ, α = 90°, β = 107.975(2)°, γ = 90°, V = 2809.8(4) Å3Å3, and Z = 4. Compound 3c crystallizes in the monoclinic space group P 21/n with a = 10.2816(16) ÅÅ, b = 18.080(3) ÅÅ, c = 15.637(2) ÅÅ, α = 90°, β = 107.076(4)°, γ = 90°, V = 2778.6(7) ÅÅ3, and Z = 4.The use of inexpensive, eco-friendly and readily available reagents, easy work-up, and high purity products makes the procedure a convenient and robust method for the synthesis of tandem Knoevenagel–Michael adducts.