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Updated: Jul 10, 2026

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
[Synthesis and spectral characterization of novel chiral macrocyclic dioxopolyamines]
1School of Pharmacy, Guangdong Medical College, Dongguan 523808, China. xuemeiyang131@163.com
Abstract:
Two novel chiral macrocyclic dioxopolyamines, which can be used as NMR chiral solvating agents (CSAs) for chiral carboxylic acids, were synthesized from L-proline through esterification, bridging and ring-closing reaction. With the aid of orthogonal experiments the optimum reaction conditions were determined: for (8S, 18S)-1, 4, 10, 13, 16-pentaaza-tricyclo [16.3. 0.04(4,8)] heneicosane-9,17-dione(2-a), reaction temperature 50 degrees C, reaction time 10 d, in nitrogen atmosphere, absolute MeOH, yield 34.9%, and m. p. 278-280 degrees C; for 13-phenyl-(8S, 18S)-1, 4, 10, 13,16-pentaaza-tricyclo [16.3. 0.0(4,8)] heneicosane-9,17-dione (2-b), reaction temperature at reflux, reaction time 20 d, in nitrogen atmosphere, absolute MeOH, yield 2.6%, and m. p. 243-245 degrees C. Their molecular structures were characterized by elemental analysis (EA), mass spectroscopy (MS), infrared spectroscopy (IR), and 1D and 2D nuclear magnetic resonance spectrometry (NMR). The main infrared absorption peaks and nuclear magnetic spectral bands of the compounds were assigned. The spectroscopic analytical result provides useful information for further study of the mechanism of host-guest interaction and for preparing new and effective CSAs.
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