作者:Thomas Jülich、Hartmut B. Stegmann、Karsten Krohn、Astrid Eickhoff
DOI:10.1002/mrc.1260290215
日期:1991.2
Different assignments of the coupling constants to distinct positions of chrysazin are given in the literature. Several methyl derivatives, particularly the hitherto unknown 1,8-dihydroxy-2,3-dimethyl-9,10-anthraquinone, were prepared, and their radical anions were investigated by EPR and ENDOR spectroscopy to achieve a reliable attribution of these values. The data obtained show a remarkable solvent dependence of the spin density distribution. Thus, the discrepancy mentioned above can be explained in terms of intermolecular hydrogen bond formation. Therefore, the requirements for an investigation of the semiquinones of the antitumour drug aclacinomycin A and 7-deoxyaklavinone are fulfilled. The splitting constants of the radical anions are assigned using model compounds, TRIPLE experiments and the solvent dependence. In contrast to the results obtained for daunomycin radicals, the data can be interpreted in terms of an almost rigid half-chair conformation of the A ring.
文献中给出了不同位置的金丝桃素耦合常数。我们制备了几种甲基衍生物,特别是迄今未知的 1,8-二羟基-2,3-二甲基-9,10-蒽醌,并通过 EPR 和ENDOR 光谱法研究了它们的自由基阴离子,以便可靠地确定这些值的归属。所获得的数据表明,自旋密度分布与溶剂有显著的相关性。因此,上述差异可以用分子间氢键的形成来解释。因此,研究抗肿瘤药物阿克拉霉素 A 和 7-脱氧阿克拉霉素酮的半醌类化合物的要求得到了满足。利用模型化合物、TRIPLE 实验和溶剂依赖性分配了自由基阴离子的分裂常数。与针对 daunomycin 自由基得出的结果不同,这些数据可以从 A 环几乎是刚性半椅构象的角度来解释。