Two C,N-linked dimeric 1,2-dihydro-2,2,4-trimethylquinolines, namely 6-chloro-1-(6-chloro-1,2-dihydro-2,2,4-trimethylquinolin-8-yl)-1,2-dihydro-2,2,4-trimethylquinoline (3a) and 6-ethoxy-1-(6-ethoxy-1,2-dihydro-2,2,4-trimethylquinolin-8-yl)-1,2-dihydro-2,2,4-trimethylquinoline (3b), have been prepared through a silver-catalyzed dimerization of their corresponding monomers. The effect of different silver salts on the reaction was also investigated, and the obtained results suggest that silver ions effectively catalyzed the formation of a C–N bond under these mild conditions. This represents one of the rare reports on the silver-catalyzed C–N bond formation through a coupling of a secondary amine and an activated aromatic system, via a direct C–H functionalization. Theoretical studies showed that these dimeric structures favor a conformation in which their monomer units are oriented approximately perpendicular to each other, with an intramolecular hydrogen bond (N–H distance of 2.33 A) forming between the hydrogen atom of the amine in one of the monomeric units and the tertiary nitrogen atom of the other one.

中文翻译：

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1,2-二氢-2,2,4-三甲基喹啉衍生物通过银 (I)-催化的 CH 键直接官能化的 CN 偶联

两个C,N-连接的二聚体1,2-dihydro-2,2,4-trimethylquinolines，即6-chloro-1-(6-chloro-1,2-dihydro-2,2,4-trimethylquinolin-8-yl )-1,2-dihydro-2,2,4-trimethylquinoline (3a) 和 6-ethoxy-1-(6-ethoxy-1,2-dihydro-2,2,4-trimethylquinolin-8-yl)-1 ,2-二氢-2,2,4-三甲基喹啉 (3b) 是通过其相应单体的银催化二聚反应制备的。还研究了不同银盐对反应的影响，所得结果表明银离子在这些温和条件下有效催化了 C-N 键的形成。这代表了银催化的 C-N 键形成的罕见报道之一，通过仲胺和活化的芳香系统的偶联，通过直接的 C-H 官能化。