Synthesis of Biologically Relevant Compounds Catalyzed By Metal Porphyrin Complexes

The direct amination of hydrocarbons is a reaction of great synthetic interest because of the biological and pharmaceutical relevance of aza-derivatives. For several years we have studied the formation of C-N bonds using aryl azides (ArN₃)¹ as nitrogen sources and metal porphyrins as catalysts. Amongst all the metal porphyrin catalysts,² ruthenium porphyrins show a good catalytic activity in both inter- and intramolecular transfer of a nitrene functionality “ArN” from aryl azides into C-H bonds. The sustainability of the synthetic procedure is related to the high atom efficiency of azides which insert the aza-fragment into the organic skeleton with the formation of benign molecular nitrogen as the only stoichiometric side product.

Herein we report the use of ruthenium porphyrins to promote the synthesis of biologically interesting compounds such us: a) α- and β-amino ester by amination of benzylic C−H bonds. The methodology was also effective in synthesizing two derivatives of methyl L-3-phenyllactate in order to convert one of them into the corresponding β-lactam;³ b) dihydrophenanthridines and phenanthridines, important core structures in a large class of pharmaceutical compounds, through the intramolecular amination of several 2-azido biaryls;⁴ c) C3-functionalized indoles by an intermolecular reaction of aryl azides with alkynes. Several derivatives were synthesized with yields up to 95%, high regioselectivity, and without requiring the time consuming prefunctionalization of reagents and the addition of oxidants and/or additives.⁵

In addition, we describe the catalytic activity of glicoporphyrin derivatives in amination reactions. It is worth noting that the use of these catalytic materials with very low toxicity could enhance the eco-sustainability of the entire synthetic process.

References:

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