Thermal oligomerisation of aryl isocyanides: formation of pyrazino[1,2-a:4,5-a']diindoles and indigo diarylimines.
The aryl isocyanides 1-4 are converted at 150 degrees C into the hexameric pyrazino[1,2-a:4,5-a']diindoles 15-19. 4-Fluorophenyl isocyanide, when heated at 135 degrees C, gave the hexamer 19 and the tetrameric indigo di-arylimine 9, and when kept at ambient temperature gave mainly the tetramer 9 in low yield. The structures of the hexamer 19 and the tetramer 9 were established by X-ray crystallography. Mechanisms are proposed for the oligomerisation reactions.
Boeyens
Jan C A
JC
School of Chemistry, University of the Witwatersrand, Private Bag 3, WITS2050, Johannesburg, South Africa.
Cook
Leanne M
LM
Ding
Yunxiang
Y
Fernandes
Manuel A
MA
Reid
David H
DH