Salem Mostafa E, Ahmed Ashour A, Shaaban Mohamed R, Shibl Mohamed F, Farag Ahmad M
Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt.
Department of Chemistry, Faculty of Science, Cairo University, Giza 12613, Egypt; Institute of Physics, Rostock University, 18051 Rostock, Germany; Steinbeis GmbH & Co. KG für Technologietransfer, 70174 Stuttgart, Germany.
Spectrochim Acta A Mol Biomol Spectrosc. 2015 Sep 5;148:175-83. doi: 10.1016/j.saa.2015.03.102. Epub 2015 Apr 2.
Pyrazolo[1,5-a]pyrimidine, triazolo[1,5-a]pyrimidine, and pyrimido[1,2-a]benzimidazole, pyrido[1,2-a]benzimidazole ring systems incorporating phenylsulfonyl moiety were synthesized via the reaction of 3-(N,N-dimethylamino)-1-(thiophen-2-yl)-2-(phenylsulfonyl)prop-2-en-1-one derivatives with the appropriate aminoazoles as 1,3-binucleophiles and 1H-benzimidazol-2-ylacetonitrile using conventional methods as well as microwave irradiation. The regioselectivity of the cyclocondensation reactions was confirmed both experimentally by alternative synthesis of reaction products and theoretically using ab initio quantum chemical calculations namely the Density Functional Theory (DFT). The theoretical work was carried out using the Becke, three parameter, Lee-Yang-Parr hybrid functional (B3LYP) combined with the 6-311++G(d,p) basis set. It was found that the final cyclocondensation reaction product depends mainly on the initial addition to the activated double bond by the nitrogen atom of the 1,3-binucleophiles that has the higher electron density.
通过3-(N,N-二甲基氨基)-1-(噻吩-2-基)-2-(苯基磺酰基)丙-2-烯-1-酮衍生物与适当的氨基唑作为1,3-双亲核试剂以及1H-苯并咪唑-2-基乙腈反应，采用常规方法以及微波辐射合成了含有苯磺酰基部分的吡唑并[1,5-a]嘧啶、三唑并[1,5-a]嘧啶、嘧啶并[1,2-a]苯并咪唑、吡啶并[1,2-a]苯并咪唑环系。通过反应产物的替代合成实验以及使用从头算量子化学计算即密度泛函理论(DFT)从理论上证实了环缩合反应的区域选择性。理论工作使用Becke三参数Lee-Yang-Parr杂化泛函(B3LYP)结合6-311++G(d,p)基组进行。发现最终的环缩合反应产物主要取决于具有较高电子密度的1,3-双亲核试剂的氮原子对活化双键的初始加成。
