Synthesis Of Benzo[a]Carbazoles By Oxidative Photochemical Cyclization

This thesis deals with the oxidative photochemical cyclization of ethyl 3-(indol-3-yl)-3-oxo-2-phenylpropanoate derivatives. It consists of two parts.In the first section, various methods reported in literature for the synthesis of benzo[a]carbazole derivatives are reviewed according to the reaction types.The second section describes my own research during the period of my graduate study. They are summarized as follows.The copper-catalyzed Ullmann-Hurtley coupling reaction was employed to realize the α-arylation of ethyl 3-(1-methyl-lH-indol-3-yl)-3-oxo-propanoates. The thus formed ethyl 3-(indol-3-yl)-3-oxo-2-arylpropanoates acted as the substrates for the oxidative photochemical cyclization towards benzo[a]carbazole derivatives. An extensive exploration of the reaction conditions with ethyl 3-(indol-3-yl)-3-oxo-2-phenyl propanoate as the substrate indicated that the desired photo electrocyclization didn’t take place under the reported conditions, but could be prompted by CuBr2. The scope of this reaction was investigated by applying the optimized conditions to variously substituted ethyl 3-(indol-3-yl)-3-oxo-2-arylpropanoates. This study not only provides a new approach towards benzo[α]carbazole structural moiety, but also helps to broaden the scope of oxidative photochemical cyclization in the synthesis of aromatic heterocycles.