Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes.
Quinoline synthesis: scope and regiochemistry of photocyclisation of substituted benzylidenecyclopentanone O-alkyl and O-acetyloximes.
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喹啉合成：取代的亚苄基环戊酮 O-烷基和 O-乙酰肟光环化的范围和区域化学。
DOI：
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发表时间：
2007
影响因子：
3.2
通讯作者：
A. C. Pratt
中科院分区：
文献类型：
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作者：
M. Austin;Oliver J. Egan;Raymond Tully;A. C. Pratt
取代的2-亚苄基环戊酮O-烷基和O-乙酰肟在甲醇中的辐射提供了方便的合成烷基，烷氧基，羟基，乙酰氧基，氨基，二甲氨基和苯并取代的环状喹啉。对位取代基产生6-取代的-2，3-二氢-1H-环戊二烯并[B]喹啉，其中8-取代的产物由邻位取代的原料获得。间位取代的前体的反应是高度区域选择性的，烷基取代基导致5-取代的2，3-二氢-1H-环戊二烯并[B]喹啉，更强的给电子取代基通常导致7-取代的产物。2-呋喃亚甲基和2-噻吩亚甲基类似物分别产生成环的呋喃并-和噻吩并-[2，3e]吡啶。顺序的E-至Z-亚苄基异构化和六个π-电子环化步骤导致形成短寿命的二氢喹啉中间体，其通过消除醇或乙酸而自发芳香化。对于2-亚苄基环戊酮O-烯丙基肟，单重激发态参与这两个步骤。
Irradiation of substituted 2-benzylidenecyclopentanone O-alkyl and O-acetyloximes in methanol provides a convenient synthesis of alkyl, alkoxy, hydroxy, acetoxy, amino, dimethylamino and benzo substituted annulated quinolines. para-Substituents yield 6-substituted-2,3-dihydro-1H-cyclopenta[b]quinolines with 8-substituted products being obtained from ortho-substituted starting materials. Reactions of meta-substituted precursors are highly regioselective, with alkyl substituents leading to 5-substituted 2,3-dihydro-1H-cyclopenta[b]quinolines and more strongly electron-donating substituents generally resulting in 7-substituted products. 2-Furylmethylene and 2-thienylmethylene analogues yield annulated furo- and thieno-[2,3e]pyridines respectively. Sequential E- to Z-benzylidene group isomerisation and six pi-electron cyclisation steps result in formation of a short-lived dihydroquinoline intermediate which spontaneously aromatises by elimination of an alcohol or acetic acid. For 2-benzylidenecyclopentanone O-allyloxime, singlet excited states are involved in both steps.
影响因子：
5.2
作者：
Xichen Lin;Didier Stien;S. Weinreb
通讯作者：
Xichen Lin;Didier Stien;S. Weinreb