两类三组份反应产物：1,3-恶嗪及嘧啶-2-酮类化合物的质谱学行为研究

电喷雾质谱被应用于分辨2-氨基-1,3-恶嗪及六氢化-4-苯基-吡喃2,3-d]嘧啶-2-酮的杂环结构。两类化合物均为三组份反应的产物，且其杂环的结构很难用NMR判断。实验首次系统研究了两类化合物的质谱学行为（包括氘代实验和高分辨质谱研究），发现前者在CID实验中丢失CH2N2和HCNO，而后者为直接丢失尿素。这些特征丢失为该类衍生物的结构判断，尤其是高通量的合成产物分析提供了重要的依据。

Fragmentation Study of 2‐Amino‐4H‐1,3‐oxazines and Octahydro‐4‐phenyl‐2H‐pyrano[2,3‐d]pyrimidin‐2‐ones: Identification of Heterocyclic Six‐membered Ring in Three‐component Reactions

The fragmentation behavior of ten 2‐amino‐4H‐1,3‐oxazines and seven octahydro‐4‐phenyl‐2H‐pyrano2,3‐d]‐pyrimidin‐2‐ones was investigated by electrospray ionization tandem mass spectrometry (ESI‐MSⁿ). When the precursor ions were protonated oxazines, two predominant fragmentation pathways were observed with elimination of CH₂N₂ and HCNO, respectively. The product ion M+H?60]⁺ could be observed from both pathways. While in the type of pyrimidin‐2‐ones, only direct loss of 60 Da (urea) could be observed. The fragmentation pathways were investigated by high‐resolution mass spectrometry and deuterium‐labeling experiments, and the characteristic fragmentations presented here could be convenient for future identification of resembled derivatives, especially in high throughput screening combinatorial chemistry.