Seldes A M, D'Accorso N, Souto M F, Alho M M, Arabehety C G
Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, LANAIS-EMAR (CONICET-FCEN), Pabellón 2, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
J Mass Spectrom. 2001 Sep;36(9):1069-73. doi: 10.1002/jms.212.
The 5-substituted tetrazole ring was reacted in the gas phase with an acyl ion generated as the secondary reactive chemical ionization plasma in the mass spectrometer. The product ions obtained, among others, were proposed as the rearranged 2,5-disubstituted-1,3,4-oxadiazole nucleus. Its structure was demonstrated by comparison of the product ion spectrum of the 2,5-disubstituted-1,3,4-oxadiazole derivative obtained by condensed-phase reaction and the product ion spectrum of the oxadiazole derivative generated in situ by reaction of the 5-substituted tetrazole derivative with the acyl plasma. It was proposed that the mechanism of this transformation involved the presence of an acylated tetrazole intermediary, which could not be isolated in the condensed phase, followed by the rearrangement, with nitrogen loss, to afford the oxadiazole derivative. Under our conditions we were able to isolate the intermediate ion in the first field free region and demonstrate its structure by collision induced dissociation-tandem mass spectrometry.
5-取代四唑环在气相中与作为质谱仪中二级反应性化学电离等离子体产生的酰基离子发生反应。所获得的产物离子中，除其他外，有人提出其为重排的2,5-二取代-1,3,4-恶二唑核。通过比较缩合相反应得到的2,5-二取代-1,3,4-恶二唑衍生物的产物离子光谱与5-取代四唑衍生物与酰基等离子体反应原位生成的恶二唑衍生物的产物离子光谱，证实了其结构。有人提出，这种转化的机制涉及酰化四唑中间体的存在，该中间体在凝聚相中无法分离，随后发生重排，伴随氮的损失，从而得到恶二唑衍生物。在我们的条件下，我们能够在第一个无场区分离出中间离子，并通过碰撞诱导解离串联质谱法证实其结构。
