Study Of The Syntheses Of Benzocarbazoles And Indolocarbazoles

This thesis describes my study on the synthetic methodologies for benzocarbazoles and indolocarbazoles. The thesis is divided into the following three chapters.In the first chapter, the general methods for the synthesis of benzocarbazoles and indolocarbazoles are introduced with an emphasis on the recent progress made in the related field.The second and the third chapters deal with the research works of my graduate study, which are summarized as follows.(1) A new photochemical method for the synthesis of benzo[a]carbazoles and indolo[2,3-a]carbazoles has been developed. This method employs the photoinduced and carbene-mediated intramolecular C-H insertion as the key step, and is advantageous in terms of simplicity and broad scope. In this way, a-diazo-1-methyl-p-oxo-2-phenyl-1H-indole-3-propanoates and a-diazo-1-methyl-β-oxo-2-phenyl-1H-indole-3-propanenitriles can be converted to the corresponding6-ethoxycarbonyl-5-hydroxy-benzo[a]-carbazoles and6-cyano-5-hydroxy-benzo[a]carbazoles in high yields. This protocol is applicable to the synthesis of natural products6-cyano-5-methoxy-indolo[2,3-a]carbazoles and their derivatives. As such, three derivatives of6-cyano-5-methoxy-indolo[2,3-a]carbazoles have been prepared by using this method.(2) Study has been conducted on utilizing the oxidative coupling reaction of P-oxo-2-arylindole-3-propionitrile (or ethyl propionate) to prepare benzo[a]carbazoles and indolo[2,3-a]carbazoles. The experimental results show that by using Ag2O as oxidant and Cs2CO3as base, β-oxo-2,2’-bisindole-3-propionitriles react smoothly to give6-cyano-5-hydroxy-indolo[2,3-a]carbazoles in high yields. When β-oxo-2-phenylindole-3-propionitrile and β-oxo-2-phenylindole-3-ethyl propionate were used as the reaction substrates, the expected products,6-hydroxy-5-cyano-11-methyl-11H-benzo[a]carbazole and6-hydroxy-11-methyl-11H-benzo[a] carbazole-5-ethyl formate, were obtained as well, but the yields were only moderate.