Department of Chemistry, University of Connecticut, Unit 3060, Storrs, Connecticut 06269-3060, United States.
Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2084, United States.
J Org Chem. 2022 Sep 16;87(18):12096-12108. doi: 10.1021/acs.joc.2c01202. Epub 2022 Sep 6.
Triple OsO-mediated dihydroxylation of -tetrakis(pentafluorophenyl)porphyrin formed a non-aromatic hexahydroxypyrrocorphin as a single stereo-isomer. A one-step oxidative conversion of all three diol functionalities to lactone moieties generated three out of the four possible porphotrilactone regioisomers that were spectroscopically and structurally characterized. This conversion recovered most of the porphyrinic macrocycle aromatic ring current, as seen in their H NMR spectra and modeled using DFT computations. Stepwise OsO-mediated dihydroxylations of porpho-mono- and -di-lactones generated intermediate oxidation state compounds between the pyrrole-three pyrroline macrocycle of the pyrrocorphin and the pyrrole-three oxazolone chromophore of the trilactones. The aromaticity of these chromophores was reduced with increasing number of oxazolone to pyrroline replacements, showing the importance for the presence of three lactone moieties for the retention of the macrocycle aromaticity in the tris-β,β'-modified macrocycles. This work first describes hexahydoxypyrrocorphins, porphotrislactones, and the oxidation state intermediates between them; furthers the understanding of the roles of β-lactone moieties in the expression of porphyrinic macrocycle aromaticity; and generally broadens access to chemically stable pyrrocorphins and pyrrocorphin analogues.
三氧化锇介导的 -四（五氟苯基）卟啉的二羟基化形成了一种非芳香的六羟基吡咯并[g]卟啉，作为单一的立体异构体。三步法将所有三个二醇官能团氧化转化为内酯部分，生成了四个可能的卟吩并三内酯区域异构体中的三个，并用光谱和结构进行了表征。这种转化恢复了卟啉大环的大部分环电流，这在它们的 NMR 谱中可以看到，并通过 DFT 计算进行了模拟。分步三氧化锇介导的卟啉单-和-二内酯的二羟基化生成了在吡咯-三吡咯啉大环和三内酯的吡咯-三恶唑啉生色团之间的氧化态中间化合物。这些生色团的芳香性随着 oxazolone 取代吡咯啉的数量增加而降低，表明对于保留大环芳香性而言，三个内酯部分的存在对于三-β，β'-修饰大环中的大环芳香性至关重要。这项工作首次描述了六氢氧基吡咯并[g]卟啉、卟吩并三内酯以及它们之间的氧化态中间体；进一步理解了β-内酯部分在卟啉大环芳香性表达中的作用；并普遍拓宽了对化学稳定的吡咯并[g]卟啉和吡咯并[g]卟啉类似物的获取途径。
