Antitumour polycyclic acridines. Part 1. Synthesis of 7H-pyrido- and 8H-quino-[4,3,2-kl]acridines by Graebe–Ullmann thermolysis of 9-(1,2,3-triazol-1-yl)acridines: application of differential scanning calorimetry to predict optimum cyclisation conditions
作者:Damien J. Hagan、Elena Giménez-Arnau、Carl H. Schwalbe、Malcolm F. G. Stevens
DOI:10.1039/a702299i
日期:——
The thermal decomposition of a series of acridines
substituted in the
9-position with 1,2,3-triazol-1-yl, benzotriazol-1-yl and
naphthotriazol-1-yl groups has been studied by differential scanning
calorimetry. Whereas the monocyclic triazole 7a shows a discrete melting
endotherm followed by a decomposition exotherm corresponding to
formation of the 7H-pyrido[4,3,2-kl]acridine 8, in the
benzotriazoles 10aâe and naphthotriazole 10f these processes
coincide with a single sharp exothermic transition attributed to
cyclisation to polycyclic acridines 11aâf, respectively. The
optimum conditions for the preparative scale synthesis of polycyclic
acridines from triazole precursors utilised boiling diphenyl ether as
the decomposition medium. A benzotriazol-1-ylacridine 10e substituted in
the peri position with a methyl group behaved anomalously: as
well as affording the expected
8H-quino[4,3,2-kl]acridine 11e, cyclisation also led
to radical mediated loss of the methyl group to form the unsubstituted
8H-quino[4,3,2-kl]acridine 11a and H-abstraction from
the methyl group leading to the benzoazepinoacridine 12. Radical
cyclisation of 9-(2-iodoanilino)acridine 16 also gave
8H-quino[4,3,2-kl]acridine 11a. The crystal structure
of 11a confirms the 8H tautomer arrangement with intermolecular
N8âH · · ·
N13 hydrogen bonding and exhibits a polycyclic system
that is planar with rms deviation 0.044 Ã
.
差示扫描量热法研究了一系列在 9 位被 1,2,3-三唑-1-基、苯并三唑-1-基和萘并三唑-1-基取代的吖啶类化合物的热分解过程。单环三唑 7a 显示了一个离散的熔化端温度,随后是与 7H-吡啶并[4,3,2-kl]吖啶 8 的形成相对应的分解放热,而在苯并三唑 10aâe 和萘并三唑 10f 中,这些过程分别与环化成多环吖啶 11aâf 的单一急剧放热转变相吻合。利用沸腾的二苯醚作为分解介质,是以三唑前体为原料制备合成多环吖啶类化合物的最佳条件。在围位被甲基取代的苯并三唑-1-基吖啶 10e 表现异常:除了得到预期的 8H-喹啉并[4,3,2-kl]吖啶 11e 外,环化还导致甲基在自由基介导下脱落,形成未取代的 8H-喹啉并[4,3,2-kl]吖啶 11a,并从甲基析出 H,得到苯并氮杂环吖啶 12。9-(2-iodoanilino)acridine 16 的 Radical cyclisation 也得到了 8H-喹啉并[4,3,2-kl]吖啶 11a。11a 的晶体结构证实了分子间 N8âH Â- Â- Â- Â- N13 氢键的 8H 同分异构体排列,并显示出一个均方根偏差为 0.044 Ã 的平面多环体系。