The single crystal X-ray structure of the novel steroid derivative, 6E-hydroximino-androst-4-ene-3,17-dione (C19H25NO3) (code name RB-499), possessing antiproliferative activity against various cell lines is presented. The analysis produced the following results: chemical formula C19H25NO3; Mr = 315.40; crystals are orthorhombic space group P212121 with Z = 4 molecules per unit cell with a = 6.2609(2), b = 12.5711(4), c = 20.0517(4) Å,Vc = 1578.18(7) Å3, crystal density Dc = 1.327 g/cm³. Structure determination was performed by direct methods, Fourier and full-matrix least-squares refinement. Hydrogens were located in the electron density and refined in position with isotropic thermal parameters. The final R-index was 0.0324 for 3140 reflections with I > 2σ and 308 parameters. The Absolute Structure Parameter − 0.07(5) confirms the correct allocation of the absolute configuration. The presence of the double bond C=O at position 3 in Ring A has caused a distortion from the usual chair conformation and created an unusual distorted sofa conformation folded across an approximate m-plane through C(1)–C(4). Ring B is a distorted chair, its conformation being influenced by the presence of the C(6)=N(6)–O(6)H group in position 6. Ring C is a symmetrical chair. Ring D exhibits both a distorted mirror symmetry conformation [influenced by the C(17)=O(17) group] and a distorted twofold conformation. DFT calculations indicated some degree of flexibility in rings A, C and D with ring A showing the greatest variation in torsion angles. The crystal packing is governed by H-bonds involving O(3), O(6) and O(17). DFT calculations of bond distances and angles, optimized at the B3LYP/6–31++G(d,p) level, were in good agreement with the X-ray structure.Graphical AbstractRing A conformations: (a) Experimental and (b) Calculated. The differences in torsion angle values indicate a degree of flexibility in the ring. The ring conformations are shown in Figures (ii) and (iv) respectively (drawn with BIOVIA [12]. Regions A1 and A2 are approximately planar in both, being planar within 0.048 Å and 0.105 Å respectively.

中文翻译：

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甾体肟 6E-Hydroximino-androst-4-ene-3,17-dione (C19H25NO3) 具有抗增殖活性的分子的晶体和分子结构以及 DFT 计算

介绍了新型类固醇衍生物 6E-hydroximino-androst-4-ene-3,17-dione (C19H25NO3)（代号 RB-499）的单晶 X 射线结构，对各种细胞系具有抗增殖活性。分析得出以下结果：化学式 C19H25NO3；先生 = 315.40; 晶体是正交空间群 P212121，每个晶胞 Z = 4 个分子，a = 6.2609(2), b = 12.5711(4), c = 20.0517(4) Å,Vc = 1578.18(7) Å3，晶体密度 Dc27 = 1。克/立方厘米。通过直接方法、傅立叶和全矩阵最小二乘法精修进行结构测定。氢位于电子密度中，并在具有各向同性热参数的位置上进行细化。对于 I > 2σ 和 308 个参数的 3140 次反射，最终 R 指数为 0.0324。绝对结构参数 - 0。07(5) 确认绝对配置的正确分配。环 A 中第 3 位双键 C=O 的存在导致了通常椅子构象的变形，并产生了一个不寻常的扭曲沙发构象，折叠通过 C(1)–C(4) 穿过近似 m 平面。环 B 是一个扭曲的椅子，它的构象受到位置 6 中 C(6)=N(6)–O(6)H 基团的影响。环 C 是一个对称的椅子。环 D 表现出扭曲的镜像对称构象 [受 C(17)=O(17) 组的影响] 和扭曲的双重构象。DFT 计算表明环 A、C 和 D 具有一定程度的灵活性，其中环 A 的扭转角变化最大。晶体堆积由涉及 O(3)、O(6) 和 O(17) 的 H 键控制。键距和角度的 DFT 计算，在 B3LYP/6-31++G(d,p) 水平优化，与 X 射线结构非常一致。图形抽象环 A 构象：（a）实验和（b）计算。扭转角值的差异表明环的柔性程度。环构象分别显示在图 (ii) 和 (iv) 中（用 BIOVIA [12] 绘制。区域 A1 和 A2 在两者中都近似平面，分别在 0.048 Å 和 0.105 Å 内为平面）。