Coumarin is one of the basic structures of naturally oxygen heterocyclic compound, which was investigated in this paper for its gas-phase fragmentation behaviors using electrospray quadrupole extractive orbitrap mass spectrometry in the positive mode. The possible fragmentation pathways were proposed based on ESI-MS/MS data and theory calculation. The elimination of two CO and CO2 were observed for protonated coumarin, which was followed by the formation of a stabilized seven-member, six-member and five-member ring carbocation by loss of C2H2. The possible protonation sites occurred at oxygen 11 atom of coumarin was the main fragmentation pathways. The relative abundance of characteristic fragment ions and the energy-resolved breakdown curves were used to confirm the cleavage mechanism of protonated coumarin. The methodology and results of present work would contribute to the chemical structure identification of other coumarins.

中文翻译：

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ESI-QE-Orbitrap-MS / MS结合DFT计算得出质子化香豆素的裂解途径。

香豆素是天然氧杂环化合物的基本结构之一，本文采用电喷雾四极杆萃取式轨道质谱仪以正模式对其气相裂解行为进行了研究。根据ESI-MS / MS数据和理论计算，提出了可能的裂解途径。观察到质子化香豆素消除了两个CO和CO2，随后通过损失C2H2形成了稳定的七元，六元和五元环碳正离子化。可能的质子化位点发生在香豆素的氧11原子上，这是主要的碎裂途径。利用特征碎片离子的相对丰度和能量分辨的分解曲线确定了质子化香豆素的裂解机理。