Synthesis and isolation of iodocarbazoles. Direct iodination of carbazoles by N-iodosuccinimide and N-iodosuccinimide-silica gel system

SERGIO M. BONESI, ROSA ERRA-BALSELLS

JOURNAL OF HETEROCYCLIC CHEMISTRY

HeteroCorp

Lugar: USA; Año: 2001 vol. 38 p. 77 - 87

0022-152X

Carbazole undergoes electrophilic aromatic substitution with various iodinating agents. Although, 3-iodocarbazole and 3,6-diiodocarbazole obtained by iodination of carbazole were isolated and characterized sometime ago, 1-iodocarabzole, 1,6-diiodocarbazole and 1,3,6-triiodocarbazole have never been isolated from the reaction mixture. The preparation and subsequent isolation and characterization are reported. As iodinating reagents, NaIO4/I2 and NaIO4/KI mixtures in (i) ethanol doped with catalytic amount of sulfuric acid and in (ii) acetic acid, and N-iodosuccinimide and N-iodosuccinimide-silica gel in dichloromethane and in chloroform have been used and their uses have been compared. The iodination reaction of different carbazoles such as 2-acetyloxycarbazole, 3-bromocarbazole and 3-nitrocarbazole was also studied and teh corresponding iododerivatives are described for the first time . semiempirical PM3 calculations have been performed in order to predict reactivity of carbazole, substituted carbazoles and iodocarbazoles. theoretical and experimental results are discussed briefly.