An alternative to ‘propylene/Leonard linker’ for studying arene interactions in flexible pyrazolo[3,4-d]pyrimidine core based models both at molecular and supramolecular levels
作者:Kamlakar Avasthi、Amantullah Ansari、Ruchir Kant、Prakas R. Maulik、Krishnan Ravikumar、Partha Chattopadhyay、Nirmal D. Adhikary
DOI:10.1039/c0ce00336k
日期:——
An alternative C-3 linker to âpropylene/Leonard linkerâ is proposed for studying arene interactions in face-to-face (offset) mode. The two new flexible symmetrical compounds with an electron deficient pyrazolo[3,4-d]pyrimidine core and biologically important isomeric purine systems and one dissymmetrical compound with a pyrazolo[3,4-d]pyrimidine core and electron-rich carbazole residue at the termini of the new linker show folding due to intramolecular ÏâÏ interactions by both 1H NMR in solution and X-ray crystallography in the solid state. Surprisingly, the replacement of the 4-methylsulfanyl group of the dissymmetrical compound by an electron donating methoxy group shows open conformation in the solid state by X-ray crystallography. The fifth symmetrical compound with an electron-rich carbazole residue at the termini of new linker, however, shows the normally expected open conformation.
为研究面对面(偏移)模式下的炔类相互作用,提出了一种替代 "丙烯/莱昂纳德连接体 "的 C-3 连接体。通过溶液中的 1H NMR 和固态中的 X 射线晶体学分析,两个以缺电子的吡唑并[3,4-d]嘧啶为核心、具有重要生物学意义的异构嘌呤系统的新型柔性对称化合物,以及一个以吡唑并[3,4-d]嘧啶为核心、在新连接体末端具有富电子咔唑残基的不对称化合物,都显示出分子内ÏâÏ相互作用导致的折叠。令人惊讶的是,通过 X 射线晶体学研究,用一个电子捐赠的甲氧基取代不对称化合物中的 4-甲硫基,在固态下显示出开放构象。第五种对称化合物在新连接体的末端含有一个富电子咔唑残基,但却显示出正常预期的开放构象。