摘要描述了一种环境友好,简单,有效和方便的方法,该方法用于在水性介质中在KHSO 4辅助的超声辐射下合成新型吡唑并[1,5- a ]嘧啶衍生物。3-(4-甲氧基苯基)-3-氧代丙烷腈与水合肼在回流的乙醇中反应,得到5-(4-甲氧基苯基)-1 H-吡唑-3-胺。3-氨基吡唑与甲酰化的活性质子化合物的缩合以高至优异的产率提供了吡唑并嘧啶。通过IR,1 H NMR,13确认合成的化合物的化学结构和区域选择性1 H NMR和质谱数据。对所选化合物进行了X射线晶体学研究。此外,筛选了这些合成的化合物的抗炎和抗癌活性,结果令人鼓舞。该方案的主要优点是收率高,操作简单,反应时间短,并且没有苛刻的反应条件。 图形概要
Herein, a regioselective, time-efficient and one-pot route for the synthesis of diversely substituted 3-halo- and 3-nitropyrazolo[1,5-a]pyrimidines in good to excellent yields through a microwave-assisted process is provided. The reaction features a sequential cyclocondensation reaction of β-enaminones with NH-5-aminopyrazoles, followed by a regioselective electrophilic substitution with easily available
在此,提供了一种区域选择性,省时和单反应路线,用于通过微波辅助方法以良好至优异的产率合成不同取代的3-卤代和3-硝基吡唑并[1,5- a ]嘧啶。该反应的特征在于β-烯酮与NH-5-氨基吡唑的顺序环缩合反应,然后用容易获得的亲电试剂进行区域选择性亲电取代。该方法的特点是反应时间短,产率高,操作简便,底物范围广和适用范围广。此外,这些3-官能化的杂环已成功地用于合成3-炔基和3-氨基吡唑并[1,5- a ]嘧啶,产率高达92%。
Mg–Al hydrotalcites as efficient catalysts for aza-Michael addition reaction: A green protocol
作者:Mohamed Mokhtar、Tamer S. Saleh、Sulaiman N. Basahel
DOI:10.1016/j.molcata.2011.11.015
日期:2012.2
Mg-Al hydrotalcite was synthesized by a co-precipitation method. We have studied the effect of calcination temperature and hydration of the calcined phases on their catalytic activity for the synthesis of pyrazolo[1,5-a]pyrimidine derivatives (aza-Michael addition product). The structure of the as-synthesized sample and the presence of the anions in the interlayer galleries of hydrotalcites, have been determined by X-ray diffraction and FTIR spectroscopy. On calcining the material at 450 degrees C, it was amorphous periclase phase. Re-hydration of the calcined phase resulted in the formation of hydrotalcite-like phase. Such treatment to the as-synthesized hydrotalcite significantly changed the pore structure and the BET-surface area as determined from N-2 physisorption at 77 K. The as-synthesized Mg-Al-hydrotalcite catalyst was found to be the most efficient for the aza-Michael reaction relative to the activated solid catalysts tested. The high performance of this catalyst was attributed to the co-operative contribution of its acidic and basic sites. We have shown that this microwave assisted reaction provides an eco-friendly alternative to the conventional syntheses where soluble bases are used. Furthermore, the reaction was performed over a considerably shorter time scale and generated significantly higher yields than traditional methods. (C) 2011 Elsevier B.V. All rights reserved.