Preparation of Indoles and Oxindoles from<i>N</i>-(<i>tert</i>-Butoxycarbonyl)-2-alkylanilines
作者:Robin D. Clark、Joseph M. Muchowski、Lawrence E. Fisher、Lee A. Flippin、David B. Repke、Michel Souchet
DOI:10.1055/s-1991-26597
日期:——
Treatment of dilithiated N-(tert-butoxycarbonyl)anilines 1 with dimethylformamide or carbon dioxide furnishes intermediates 3, 5, that are easily converted to N-(tert-butoxycarbonyl)indoles 4 and oxindoles (indol-2(3H)-ones, 7), respectively. Condensation of dilithiated 1 with N-methoxy-N-methylamides provides ketones 9 which are cyclized upon trifluoroacetic acid treatment to either 2-substituted 1-(tert-butoxycarbonyl)indoles 10 or 2-substituted indoles 11 depending on the reaction time. This general methodology has been applied to efficient synthesis of 1,2-alkyl-bridged indoles 12, 1,3,4,5-tetrahydrobenz[c,d]indole (16), 2a,3,4,5-tetrahydrobenz [c,d]indol-2(1H)-one (18), and 1-(tert-butoxycarbonyl) -1H-pyrrolo[2,3-b]pyridine (21).
使用双锂化的N-(叔丁氧羰基)苯胺1与二甲基甲酰胺或二氧化碳反应,可得到中间体3和5,它们分别容易转化为N-(叔丁氧羰基)吲哚4和氧化吲哚(吲哚-2(3H)-酮,7)。双锂化的1与N-甲氧基-N-甲基酰胺缩合得到酮9,这些酮在三氟乙酸处理下环化,根据反应时间的不同,形成2-取代的1-(叔丁氧羰基)吲哚10或2-取代的吲哚11。这一通用方法已被应用于高效合成1,2-烷基桥联吲哚12、1,3,4,5-四氢苯[c,d]吲哚(16)、2a,3,4,5-四氢苯[c,d]吲哚-2(1H)-酮(18)以及1-(叔丁氧羰基)-1H-吡咯并[2,3-b]吡啶(21)。