Pd(II)-catalyzed double cyclization of 1,2-diarylethynes bearing an N-methyl-N-[2-(methoxycarbonyl)ethyl]amino and an aminocarbonyl group at the ortho positions of the two aromatic rings afforded the tetracyclic N-[2-(methoxycarbonyl)ethyl]indoloisoquinolinones in good to excellent yields. The N-[2-(methoxycarbonyl)ethyl] group is readily removed under basic conditions (DBU, DMF, 120 °C) to afford the corresponding tetracycles with a free indolyl nitrogen in excellent yields. The 2-(methoxycarbonyl)ethyl as a removable N-protecting group is illustrated in other Pd(II)- and Pd(0)-catalyzed and selenium-mediated transformations.

中文翻译：

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2-（甲氧羰基）乙基作为可移动的N保护基：钯（II）催化炔烃分子内缩合反应合成吲哚异喹啉酮

Pd（II）催化的在两个芳环的邻位带有N-甲基-N- [2-（甲氧基羰基）乙基]氨基和氨基羰基的1,2-二芳基乙炔的双环化反应得到四环N- [ 2-（甲氧基羰基）乙基]吲哚异喹啉酮类化合物的收率高至优异。在碱性条件（DBU，DMF，120°C）下，N- [2-（甲氧羰基）乙基]基很容易被除去，以极好的收率得到相应的带有游离吲哚基氮的四环。在其他Pd（II）和Pd（0）催化和硒介导的转化中说明了作为可移动N保护基的2-（甲氧羰基）乙基。