Organic Chemistry Department, Lomonosov Moscow State University, 119992 Moscow, Russia.
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, USA.
Molecules. 2023 Jan 18;28(3):977. doi: 10.3390/molecules28030977.
A large variety of 1,2,3-thiadiazoles and 1,2,3-triazoles are used extensively in modern pure and applied organic chemistry as important structural blocks of numerous valuable products. Creation of new methods of synthesis of these isomeric compounds requires the development of reliable analytical tools to reveal the structural characteristics of these novel compounds, which are able to distinguish between isomers. Mass spectrometry (MS) is a clear choice for this task due to its selectivity, sensitivity, informational capacity, and reliability. Here, the application of electrospray ionization (ESI) with ion detection in positive and negative modes was demonstrated to be useful in structural studies. Additionally, interconversion of isomeric 4,5-functionalized 1,2,3-triazoles and 1,2,3-thiadiazoles was demonstrated. Application of accurate mass measurements and tandem mass spectrometry in MS2 and MS3 modes indicated the occurrence of gas-phase rearrangement of 1,2,3-triazoles into 1,2,3-thiadiazoles under (+)ESI-MS/MS conditions, independent of the nature of substituents, in line with the reaction in the condensed phase. Infrared multiple photon dissociation (IRMPD) spectroscopy enabled the establishment of structures of some of the most crucial common fragment ions, including [M+H-N] and [M+H-N-RSO] species. The (-)ESI-MS/MS experiments were significantly more informative for the sulfonyl alkyl derivatives compared to the sulfonyl aryl ones. However, there was insufficient evidence to confirm the solution-phase transformation of 1,2,3-thiadiazoles into the corresponding 1,2,3-triazoles.
大量的 1,2,3-噻二唑和 1,2,3-三唑广泛应用于现代纯有机和应用有机化学中，是许多有价值产品的重要结构单元。这些异构化合物新合成方法的创建需要开发可靠的分析工具来揭示这些新型化合物的结构特征，这些工具能够区分异构体。由于选择性、灵敏度、信息量和可靠性，质谱（MS）是这项任务的明确选择。在这里，展示了正离子和负离子模式下的电喷雾电离（ESI）与离子检测在结构研究中的应用。此外，还证明了异构 4,5-官能化 1,2,3-三唑和 1,2,3-噻二唑的相互转换。在 MS2 和 MS3 模式下进行精确质量测量和串联质谱分析表明，在 (+)ESI-MS/MS 条件下，1,2,3-三唑在气相中重排为 1,2,3-噻二唑，与在凝聚相中发生的反应一致，与取代基的性质无关。红外多光子解离（IRMPD）光谱使一些最关键的常见碎片离子的结构得以建立，包括 [M+H-N] 和 [M+H-N-RSO] 物种。与芳基砜基衍生物相比，(-)ESI-MS/MS 实验对磺酰基烷基衍生物更具信息性。然而，没有足够的证据证实 1,2,3-噻二唑在溶液相中转化为相应的 1,2,3-三唑。
