Flash vacuum pyrolysis (FVP) of the oxime ethers 9–11 at 650 °C (10–2–10–3 Torr) gives products such as the nitrile 17, carbazoles 19 and 20 and acridines 18 and 21 derived from the corresponding iminyl radicals 13–15. The mechanism proposed for the formation of the acridines involves a key hydrogen abstraction by the iminyl of the adjacent N–H atom. When this route is blocked by an N-methyl group, as in 12, alternative cyclisations ensue, yielding the dihydroquinazoline 26 (via another hydrogen abstraction process) and the benzimidazole 25 (via an iminyl–imidoyl interconversion).
在650°C(10–2–10–3 Torr)下对氧
肟醚9–11进行快速真空热解(FVP),会生成如腈17、
咔唑19和20以及来自相应亚
氨基自由基13–15的
蒽啶18和21等产物。提出的
蒽啶形成机制涉及邻近N–H原子被亚
氨基关键氢抽提。当这种路径因N-甲基基团(如在12中)受到阻碍时,会发生替代环化反应,导致生成二氢
喹唑啉26(通过另一种氢抽提过程)和
苯并咪唑25(通过亚
氨基-
亚胺互转)。