A Simple Approach to the One-Pot Three Component Synthesis of 4Hpyrimido [2,1-b] benzothiazole Derivatives Using Polyethylene Glycol (PEG-400)
作者:Prabhakar Rairala、Bandi Yadagiri、Rajashaker Bantu、Vijayacharan Guguloth、Lingaiah Nagarapu
DOI:10.2174/1570178612666150113231342
日期:2015.3.3
PEG-400 was found to be an inexpensive, non-toxic and eco-friendly reaction medium for synthesis of pyramido[2,1-b]benzothiazole derivatives. Utilizing this protocol, we are capable of various pyrimido[2,1-b]benzothiazole derivatives
4a-k and 6a-d were synthesised. The reaction between aminobenzothiazole 1, aromatic aldehydes 2a-k and ethyl
acetoacetate 3/ diethyl malonate 5 at room temperature for 1-2 h furnished required compounds with good to excellent
yields (85-93%). Here we observed carboxylic acid compounds instead of ester compounds when diethyl malonate was
used as the substrate, whereas ethyl acetoacetate showed no signs. The reactions are easy to perform, atom-economic, require
less reaction time and allow generation of the biologically potent pyrimido[2,1-b]benzothiazole frameworks from
readily accessible starting materials.
研究发现,PEG-400 是合成嘧啶并[2,1-b]苯并噻唑衍生物的一种廉价、无毒且环保的反应介质。利用这一方案,我们能够合成各种嘧啶并[2,1-b]苯并噻唑衍生物 4a-k 和 6a-d。氨基苯并噻唑 1、芳香醛 2a-k 和乙酰乙酸乙酯 3/ 丙二酸二乙酯 5 在室温下反应 1-2 小时后,生成了所需的化合物,收率高达 85-93%。在这里,当丙二酸二乙酯作为底物时,我们观察到的是羧酸化合物而不是酯类化合物,而乙酰乙酸乙酯则没有任何迹象。这些反应易于进行、原子经济、所需反应时间较短,并能从容易获得的起始材料中生成具有生物活性的嘧啶并[2,1-b]苯并噻唑框架。