Cheap thiamine hydrochloride as efficient catalyst for synthesis of 4H-benzo[b]pyrans in aqueous ethanol
作者:Lu Chen、Sunan Bao、Lixiang Yang、Xian Zhang、Bin Li、Yibiao Li
DOI:10.1007/s11164-016-2843-x
日期:2017.7
Preparation of pharmaceutically active 2-amino-4H-pyran derivatives has been achieved using cheap thiamine hydrochloride as catalyst. A wide range of aromatic aldehydes easily undergo condensation with malononitrile and several kinds of 1,3-cyclohexanedione under mild condition to afford the desired product with good purity in excellent yield. This protocol has various advantages as a simple, clean, and environmentally benign three-component process.
Green approach towards the facile synthesis of dihydropyrano(c)chromene and pyrano[2,3-d]pyrimidine derivatives and their biological evaluation
作者:Pradeep K. Paliwal、Srinivasa Rao Jetti、Shubha Jain
DOI:10.1007/s00044-012-0288-3
日期:2013.6
one-pot synthesis of heteroaryl-substituted dihydropyrano(c)chromenes and pyrano[2,3-d]pyrimidines has been developed. Reaction proceeds via initial Knoevenagel, subsequent Michael and final heterocyclization reactions of heteroaryl aldehyde, malononitrile, and barbituric acid/dimedone. Triethylammonium acetate acts as a green catalyst as well as reusable solvents for this reaction. Short reaction time
已开发出一种简单有效的一锅合成杂芳基取代的二氢吡喃并(c)色烯和吡喃并[2,3- d ]嘧啶的方法。反应通过最初的Knoevenagel,随后的Michael以及杂芳基醛,丙二腈和巴比妥酸/二甲酮的最终杂环化反应进行。乙酸三乙铵充当绿色催化剂以及该反应的可重复使用溶剂。反应时间短,环境友好的程序,可重复使用性和优异的产率是该程序的主要优点。所有合成的化合物对不同的微生物污渍均显示出良好的抗菌活性,但对癌细胞系没有活性。
Polyionic liquid decorated chitosan beads as versatile metal-free catalysts for catalyzing chemical reactions in aqueous media
作者:Fatemeh Koohestani、Samahe Sadjadi
DOI:10.1016/j.molliq.2021.115754
日期:2021.7
resultant composite was subsequently utilized as a metal-free catalyst for catalyzing some classic organic transformations, including Knoevenagel condensation reaction and syntheses of tetrahydrobenzo[b]pyrans and pyrano[2,3-d]pyrimidines in aqueous media undermild reaction conditions. It was found that the novel composite could efficiently promote all of the examined reactions to afford the corresponding
提出了提高交联壳聚糖珠的催化活性的新策略。更精确地,将壳聚糖珠与戊二醛交联,然后使乙烯基官能化。在下一步中,将乙烯基官能化的珠粒与所制备的1-乙烯基-3-丁基咪唑鎓溴化物聚合,以在珠粒上提供聚离子液体。随后将所得复合材料用作无金属催化剂,用于催化一些经典的有机转化,包括Knoevenagel缩合反应以及四氢苯并[ b ]吡喃和吡喃并[2,3- d ]的合成嘧啶在温和的反应条件下于水性介质中。发现该新型复合材料可以有效地促进所有检查的反应,从而以高收率提供相应的产物。而且,该催化剂对所有反应都显示出高的可循环性。比较研究还证实,与交联的珠粒和聚离子液体相比,复合材料的活性更高。
4,4’-trimethylenedipiperidine as a nitrogen heterocycle solvent and/or catalyst: Liquid phase tandem Knoevenagel–Michael condensation
作者:Lia ZAHARANI、Nader GHAFFARI KHALIGH、Hayede GORJIAN、Mohd RAFIE JOHAN
DOI:10.3906/kim-2010-41
日期:——
Liquid phase tandem Knoevenagel-Michael condensation of various aromatic and heteroaromatic aldehydes with barbituric acid or 2-thiobarbituric acid and malononitrile was studied in a one-pot three-component reaction. For the first time, TMDP was employed as a safe and efficient solvent and/or catalyst in the liquid and aqueous ethanol medium, respectively, for the practical and eco-friendly Knoevenagel-Michael
Titanium dioxide nanoparticles as efficient catalyst for the synthesis of pyran’s annulated heterocyclic systems via three-component reaction
作者:Ladan Edjlali、Rahim Hosseinzdeh Khanamiri
DOI:10.1007/s00706-015-1624-3
日期:2016.7
were introduced as a new and efficient heterogeneous catalyst for the synthesis of pyran’s annulated heterocyclic systems via three-component reaction. The reaction was carried out between various aldehydes, malononitrile, and cyclic CH-acids in H2O as a green solvent at 50 °C during 10 h. This reaction gave pyrans containing heterocyclic compounds including nineteen derivatives in good yields. Titanium