高分辨高能量碰撞解离质谱法研究3-苯硫基吲哚衍生物裂解反应机理

Study on Fragmentation Mechanisms of 3-(Phenylthio)-1 Hindoles by High-Resolution HCD-MS/MS

采用高分辨电喷雾电离-高能量碰撞解离质谱(ESI-HCD-MS/MS)技术,结合H/D交换试验和密度泛函理论计算,对3-苯硫基吲哚衍生物质子化离子的质谱裂解反应机理进行了研究。结果表明:3-苯硫基吲哚衍生物的质子化离子在高能量碰撞解离模式下,通过苯基亲核取代重排到吲哚环的C^3位上,C-S键均裂丢失巯基自由基,产生了3-(取代苯基)-吲哚自由基阳离子;通过1,2-氢负离子迁移和C^3-S键均裂丢失苯硫自由基,则产生了吲哚自由基阳离子;通过1,4-质子迁移和C^5-S键的电荷诱导异裂,产生了3-硫代吲哚阳离子。

The fragmentation mechanism of protonated 3-（phenylthio）-lH-indoles was studied by high- resolution electrospray ionization-high-energy collisional dissociation mass spectrometry （ESLHCD-MS/MS）, in combination with H/D exchange experiments and density functional theory （DFT） calculation. It was shown that under the mode of HCD of the protonated ion of 3-（phenylthio）-lH-indoles, free radical cation of 3-（substituted phenyl）-indole was obtained through phenyl nucleophilic substitution and rearrangement at C3 of the indole ring followed by elimination of mercapto free radical by homolytic cleavage of the C--S bond; indole free radical cation was obtained through 1,2-hydride shift followed by loss of thiophenyl radical by homolytic cleavage of the Ca --S bond; and 3-thioxo-indole cation was obtained through 1,4-proton shift followed by loss of phenyl radical by charge- induced heterolytic cleavage of the C5--S bond.