Synthesis of hexahydropyrrolo[2,3-b]indole alkaloids based on the aza-Pauson-Khand-type reaction of alkynecarbodiimides.
Upon treatment with 30 mol % of Co2(CO)(8) and 30 mol % of TMTU in toluene at 70 degrees C, benzene-bridged alkynecarbodiimides efficiently underwent a 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 an angular substituent at the C(3a)-position by treatment with NaBH(4)/alkyl bromide as the crucial step.
Aburano
Daisuke
D
Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan.
Yoshida
Tatsunori
T
Miyakoshi
Naoki
N
Mukai
Chisato
C
D000478:Alkylation; D000480:Alkynes / Q000737:chemistry*; D001372:Aza Compounds / Q000737:chemistry*; D002234:Carbodiimides / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D026121:Indole Alkaloids / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D011758:Pyrroles / Q000737:chemistry*
D000480:Alkynes; D001372:Aza Compounds; D002234:Carbodiimides; D026121:Indole Alkaloids; D011758:Pyrroles; D006859:Hydrogen