Modifications of carboxyindoles on solid phase

Different solid phase modifications were studied in order to develop new and simple routes for pharmaceutically interesting highly substituted carboxyindoles. A convenient method for the preparation of 5-substituted 2-carboxyindoles and three novel direct functionalization methods for carboxyindoles were developed during this study. 5-Nitro-2-carboxyindole was synthesized easily in three steps from commercially available inexpensive 4-nitro-aniline. Through attachment of this template to solid phase followed by reduction, reductive amination, N-alkylation and cleavage, a small library of differently substituted carboxyindoles were obtained. Solid phase brominations were studied followed by palladium catalyzed Suzuki-coupling. This technology offers an efficient and selective method to introduce bromine and a new C-C-bond to 3-position of polymer bound 2-carboxyindoles. Formylation studies were also succesfull. By utilizing Vilsmeier formylation a new C-C-bond was obtained direcly and selectively at the 3-position of polymer bound 2-carboxyindoles. In solid phase metalation studies of 5-carboxyindoles a 4-position functionalization was achieved in 80 % regioselectivity. Despite the moderate regioselectivity it is obvious that ring lithiation can be adopted to solid phase.reviewe

PyOX-ligands: the asymmetric Henry reaction

Abstract: C 2 -dissymmetric PyOX-ligands have been applied to the asymmetric Henry reaction. This widely applicable reaction is easy to perform, requires no inert atmospheres or dry solvents, and gives good selectivities. By adjusting ligand side-chains, a significant impact on selectivities was observed