36602-03-6Relevant articles and documents
The Synthesis of Pyridocarbazoles from Diphenylamine Derivatives: Alternative Routes to and Relay Syntheses of Ellipticines and Olivacines
Hall, Robin J.,Marchant, Jeremy,Oliveira-Campos, Ana M. F.,Queiroz, Maria-Joao R. P.,Shannon, Patrick V. R.
, p. 3439 - 3450 (2007/10/02)
Two new synthetic routes to pyridocarbazoles are described.In the first, Goldberg-type coupling of various aryl sulfonamides with aryl bromides in the presence of copper and potassium carbonate gives N,N-diaryl sulfonamides.UV irradiation of these, in ethanol, removes the toluene-p-sulfonyl protecting groups and cyclises the diphenylamine moiety to the corresponding carbazoles.These carbazoles are established intermediates in the synthesis of several ellipticines (5,11-dimethylpyridocarbazoles).In a complementary route, a series of substituted acetanilides are similarly coupled under Goldberg conditions with 2-bromo-5-cyanotoluene to give the corresponding cyanodiphenylamines and diphenylamides.Hydrolysis of the latter gives the diphenylamines which are then oxidatively cyclised to 3-cyano-1-methylcarbazoles.Reduction of the cyanocarbazoles leads to 3-formylcarbazoles which are known intermediates for the synthesis of 5-methylpyridocarbazoles.
