Synthesis of achiral and racemic catenanes based on terpyridine and a directionalized terpyridine mimic, pyridyl-phenanthroline
作者:Jon C. Loren、Peter Gantzel、Anthony Linden、Jay S. Siegel
DOI:10.1039/b506101f
日期:——
Concatenated macrocycles containing manisyl-substituted tridentate ligands 2,2′:6′,2″-terpyridine and 2-pyridin-2-yl-1,10-phenanthroline (simply referred to as terpyridine and pyridyl-phenanthroline herein) have been prepared via dual cyclization procedures. The manisyl derivative (manisyl = 4-methoxy-2,6-dimethylphenyl) was chosen for its ability to improve solubility while simultaneously incorporating functionality. Deprotection of the methoxy groups provided a soluble ligand that was re-alkylated with an array of terminal alkyne and alkene linkers. The tridentate coordinating ability of these ligands enabled complexation with Ru(II) and Fe(II), generating achiral and racemic octahedral complexes for terpyridine and pyridyl-phenanthroline, respectively. Subsequent macrocyclization via olefin metathesis or copper-mediated alkyne coupling afforded the corresponding catenanes, and in some cases a figure-eight macrocycle. The difference in symmetry and the presence of the manisyl group allowed the distinction between the catenane and the undesired figure-eight to be made directly by 1H NMR. Metal-free achiral and racemic catenanes were obtained by liberating Fe(II) from the octahedral bound title ligands by treatment with hydrogen peroxide.
通过双环化程序制备了含有山麦冬基取代的三齿配体2,2′:6′,2″-三联吡啶和2-吡啶-2-基-1,10-菲咯啉(简称为三联吡啶和吡啶基菲咯啉)的串联大环化合物。山麦冬基衍生物(山麦冬基=4-甲氧基-2,6-二甲基苯基)因其能提高溶解性同时兼具功能性而被选用。通过脱甲基化处理得到了可溶性配体,然后与一系列末端炔烃和烯烃连接子重新烷基化。这些配体的三齿配位能力使其能够与Ru(II)和Fe(II)配位,分别生成非手性和外消旋的八面体配合物。随后通过烯烃复分解反应或铜催化的炔烃偶联反应进行大环化,得到了相应的联环化合物,在某些情况下还形成了八字形大环。对称性的差异和山麦冬基团的存在使得可以通过1H NMR直接区分联环化合物和不需要的八字形大环。通过用过氧化氢处理,使Fe(II)从八面体配合物中释放出来,得到了非手性和外消旋的无金属联环化合物。