Various 8-halogenotheophyllines (halogen = Cl, Br, I) were selectively C8 metalated by an oxidative addition of the C8–halogen bond to [Pd(PPh₃)₄] to give the Pd^II azolato complexes [1]–[3]. The complexes were protonated at the N9 nitrogen atom to yield the NH,NH-NHC (pNHC) complexes [4]BF₄–[6]BF₄. Due to the unsymmetrical nature of the backbone of the theophylline-derived pNHC ligands, two NH resonances were observed by ¹H NMR spectroscopy. In addition, 8-bromoadenine was also regioselectively C8 metalated via an oxidative addition of the C8–Br bond to [Pd(PPh₃)₄] in the presence of the proton source pyridinium tetrafluoroborate to give [7]BF₄.

中文翻译：

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氧化p- NHC配体的Pd ^II配合物通过氧化8-卤代茶碱和8-溴腺嘌呤Pd ^0的合成。

通过将[ Cd （PPh ₃）₄ ]上的C8-卤素键氧化加成，可将各种8-卤代茶碱（卤素= Cl，Br，I）选择性地C8金属化，得到Pd ^II氮杂复合物[ 1 ]-[ 3 ] 。配合物在N9氮原子处质子化，生成NH，NH-NHC（p NHC）配合物[ 4 ] BF ₄ – [ 6 ] BF ₄。由于茶碱衍生的p NHC配体骨架的不对称性质，通过¹观察到两个NH共振。1 H NMR光谱。另外，在质子源四氟硼酸吡啶鎓吡啶鎓存在下，通过将C8-Br键氧化加到[Pd（PPh ₃）₄ ]上，还对8-溴腺嘌呤进行了区域选择性的C8金属化，得到[ 7 ] BF ₄。