The influence of A steric interactions on the conformational features of benzo[g]pyridazino[1,2-b]phthalazine-6,13-dione derivatives
作者:M. Carmen Cano、Fernando Gómez-Contreras、Manuel Lora-Tamayo
DOI:10.1039/p19910000273
日期:——
moiety in methyl-substituted adducts 2a–g has been studied by X-ray diffraction and NMR spectroscopic methods. The conformational properties of ring A are controlled by the carbonyl groups on ring B through A stericinteractions. Substitution at C-1 and/or C-4 freezes the conformational equilibrium to give terminal tetrahydropyridazine rings with the substituents axially oriented or exhibiting a boat-like
与蒽环素系统有关的二氮杂四环化合物是通过苯并[ g ]邻苯二甲酰基-1,4-二酮与适当的二烯的[4 + 2]环加成反应合成的。通过X射线衍射和NMR光谱法研究了甲基取代的加合物2a – g中A环的几何结构。环A的构象性质受环B上的羰基控制通过空间相互作用。在C-1和/或C-4处的取代冻结了构象平衡,以给出末端四氢哒嗪环,该环具有轴向取向或呈船形几何形状的取代基。在C-2-C-3双键异构化产物5a - d中也发现了类似的结果,它们仅在不存在氮原子附近的取代基的情况下才由各自的加合物形成。