Substituted pyrrolo[3,4-a]carbazoles from reactions between 3-(1-methoxyvinyl)indoles and maleimides

5-Methylenolether derivatives of pyrrolo[3,4-a]carbazoles were obtained from cycloadditions between 3-(1-methoxyvinyl)-1-tosylindole and N-substituted maleimides. They were transformed into the hydroxy derivatives by treatment with H2SO4, selectively reduced to the ether by H-2/Pd-C, and in the imide moiety by L-Selectride(R). From the analogous BOC protected indole derivative the parent alpha,beta-unsaturated ketones were obtained, which were transformed into hydroxyimino compounds, and which could be deprotected by heating to the melting point. Deprotection of the tosyl derivatives was not successful. The imide part of the molecule was hydrolyzed using methanolic NaOH. The stereochemistry of all products Was elucidated mainly by spectroscopic methods, and compared with results of calculations.