A simple and efficient approach for the synthesis of 2-spirocyclopropyl-indolin-3-ones is herein described. The method involves a diasteroselective cyclopropanation of aza-aurones with tosylhydrazones, selected as versatile carbene sources, and represents a remarkable synthetic alternative to get access to this class of C2-spiropseudoindoxyl scaffolds. The reactions proceed in the presence of a base and catalytic amounts of benzyl triethylammonium chloride and well-tolerate a broad range of substituents on both aza-aurones and tosylhydrazones to afford a series of C2-spirocyclopropanated derivatives in high yields. In addition, selected functional group transformations of the final products were explored demonstrating the synthetic potential of these indole-based derivatives.

Stereoselective synthesis of 2-spirocyclopropyl-indolin-3-ones through cyclopropanation of aza-aurones with tosylhydrazones / V. Pirovano, E. Brambilla, M. Riva, S. Leoni, S. Rizzato, D. Garanzini, G. Abbiati, E. Rossi. - In: ORGANIC & BIOMOLECULAR CHEMISTRY. - ISSN 1477-0520. - 19:17(2021), pp. 3925-3931.

Stereoselective synthesis of 2-spirocyclopropyl-indolin-3-ones through cyclopropanation of aza-aurones with tosylhydrazones

Valentina Pirovano;Elisa Brambilla;Marika Riva;Silvia Rizzato;Davide Garanzini;Giorgio Abbiati;Elisabetta Rossi
2021

Abstract

A simple and efficient approach for the synthesis of 2-spirocyclopropyl-indolin-3-ones is herein described. The method involves a diasteroselective cyclopropanation of aza-aurones with tosylhydrazones, selected as versatile carbene sources, and represents a remarkable synthetic alternative to get access to this class of C2-spiropseudoindoxyl scaffolds. The reactions proceed in the presence of a base and catalytic amounts of benzyl triethylammonium chloride and well-tolerate a broad range of substituents on both aza-aurones and tosylhydrazones to afford a series of C2-spirocyclopropanated derivatives in high yields. In addition, selected functional group transformations of the final products were explored demonstrating the synthetic potential of these indole-based derivatives.
synthetic methods, indole, homogeneous catalysis
Settore CHIM/06 - Chimica Organica
apr-2021
ORGANIC & BIOMOLECULAR CHEMISTRY
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/841871
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