Co2(CO)8-Catalyzed Intramolecular Hetero-Pauson−Khand Reaction of Alkynecarbodiimide: Synthesis of (±)-Physostigmine
摘要:
Herein we describe a novel CO2(CO)(8)-catalyzed intramolecular aza-Pauson-Khand-type reaction of alkynecarbodiimide derivatives affords pyrrolo[2,3-b]indol-2-one ring systems in reasonable yields. This is the first reported CO2(CO)(8) Successfully applied in the hetero-Pauson-Khand reaction. Significantly, the transformation of one of our pyrrolo[2,3-b]indol-2-one derivatives into the indole alkaloid, (+/-)-physostigmine, was completed in a highly stereoselective manner.
ring-closing reaction to give the pyrrolo[2,3-b]indol-2-ones in good yields. These conditions could nearly suppress the formation of the urea derivatives, which were consistently observed when 10 mol % of Co2(CO)8 and 60 mol % of TMTU in benzene were used. The synthesis of the eight hexahydropyrrolo[2,3-b]indole alkaloids was accomplished from the resulting pyrrolo[2,3-b]indol-2-ones via the introduction of
在70°C下用30 mol%的Co 2(CO)8和30 mol%的TMTU在甲苯中处理后,苯桥炔烃二酰亚胺有效地进行闭环反应,得到吡咯并[2,3- b ]吲哚- 2个收率好。这些条件几乎可以抑制脲衍生物的形成,当在苯中使用10 mol%的Co 2(CO)8和60 mol%的TMTU时,可以一致地观察到。八种六氢吡咯并[2,3 - b ]吲哚生物碱的合成是通过用NaBH处理在C 3a-位引入有角取代基从所得到的吡咯并[2,3 - b ]吲哚-2-酮完成的。4/烷基溴是关键步骤。
Co<sub>2</sub>(CO)<sub>8</sub>-Catalyzed Intramolecular Hetero-Pauson−Khand Reaction of Alkynecarbodiimide: Synthesis of (±)-Physostigmine
Herein we describe a novel CO2(CO)(8)-catalyzed intramolecular aza-Pauson-Khand-type reaction of alkynecarbodiimide derivatives affords pyrrolo[2,3-b]indol-2-one ring systems in reasonable yields. This is the first reported CO2(CO)(8) Successfully applied in the hetero-Pauson-Khand reaction. Significantly, the transformation of one of our pyrrolo[2,3-b]indol-2-one derivatives into the indole alkaloid, (+/-)-physostigmine, was completed in a highly stereoselective manner.