School of Sciences, Zhejiang Sci-Tech University, Hangzhou 310018, China.
Org Biomol Chem. 2019 May 28;17(20):5075-5085. doi: 10.1039/c9ob00613c. Epub 2019 May 8.
Oxacalix[4]arenes obtained from the highly efficient, one-pot SAr reaction were post-macrocyclization functionalized through the reduction of nitro groups and hydrolysis of the ester groups to obtain several derivatives of desired solubility. The difficulties in basic hydrolysis of ester groups were overcome via developing an acid hydrolysis method for tert-butyl ester derivatives of this class. The synthesis of symmetrical oxacalix[4]arenes from an unsymmetrically substituted precursor was also explored via a multiple step fragment coupling approach. Compounds 17 & 18 adopted 1,3-alternate conformations in the solid state as most oxacalix[4]arenes did, and a chair (zigzag) conformation was revealed for tetraamido oxacalix[4]arene (6a) by X-ray single crystal analysis. The tetraureido oxacalixarene (7) showed strong association towards various anions such as F, Cl, Br, I, Ac, and HSO with a 1 : 1 stoichiometry as revealed by H NMR analysis and UV-vis measurements.
从高效一锅 SAr 反应中获得的氧杂杯[4]芳烃，通过还原硝基和水解酯基进行了后大环化官能化，得到了几种具有所需溶解度的衍生物。通过开发该类叔丁酯衍生物的酸水解方法，克服了酯基碱性水解的困难。还通过多步片段偶联方法探索了从不对称取代前体制备对称氧杂杯[4]芳烃。化合物 17 和 18 在固态中采用 1,3-交替构象，就像大多数氧杂杯[4]芳烃一样，并且通过 X 射线单晶分析揭示了四氨基氧杂杯[4]芳烃（6a）的椅（之字形）构象。四脲基氧杂杯芳烃（7）表现出对各种阴离子（如 F、Cl、Br、I、Ac 和 HSO）的强烈缔合，如 1：1 化学计量比，这是通过 1H NMR 分析和紫外可见测量揭示的。
