In the classical route of synthesizing of avanafil, the last step of the reaction uses EDCI and HOBT as an acid and amine binding agent. HOBT may contain residues of hydrazine, and potential mutagenic impurities containing acylhydrazide structures may be formed. The intermediate product (M6) of avanafil was synthesized by 6 steps using diethyl ethoxylmethylmalonate and S-methyl isothiourea semisulfide as starting materials. The potentially genotoxic impurity E (Imp-E) of avanafil was given by the reaction of M6 and hydrazine sulfate acid amine, yield of 20%. The single crystal of Imp-E was cultivated by solvent volatilization method, and its structure was analyzed by high resolution mass spectrometry (HRMS) and nuclear magnetic resonance spectroscopy (NMR). The Flack parameter of Imp-E was -0.03(3) by X-ray single crystal diffraction analysis, and the absolute configuration of Imp-E was determined as S configuration. The intramolecular / intermolecular hydrogen bonds of Imp-E make the molecules maintain a stable arrangement in space.

在阿伐那非的经典合成路线中，反应的最后一步使用 EDCI 和 HOBT 作为酸和胺结合剂。HOBT可能含有肼残留物，并且可能形成含有酰肼结构的潜在诱变杂质。以乙氧基甲基丙二酸二乙酯和S-甲基异硫脲半硫化物为原料，经6步合成阿伐那非中间产物(M6)。阿伐那非的潜在遗传毒性杂质E（Imp-E）由M6与硫酸肼酸胺反应得到，收率20%。采用溶剂挥发法培养Imp-E单晶，并通过高分辨率质谱（HRMS）和核磁共振波谱（NMR）分析其结构。X射线单晶衍射分析Imp-E的Flack参数为-0.03(3)，Imp-E的绝对构型确定为S构型。Imp-E的分子内/分子间氢键使分子在空间上保持稳定的排列。