The palladium catalyzed reductive cyclization of substituted ortho-nitrostyrenes is a powerful method for the synthesis of indoles. The reaction proceeds using CO as the reductant [1]. However CO is a highly toxic gas and its use implies the installation of expensive safety measures and high-pressure equipments. Therefore carbonylation reactions using non-gaseous CO precursors are highly desirable [2]. For our purpose we chose formate esters as the CO sources due their commercial availability and low cost. Thus, we developed a one-pot two-catalysts system composed of Ru3(CO)12 and [Pd(Phen)2][BF4]2 for the decarbonylation and the reductive cyclization step respectively. As the result various 2,6-substituted indoles were synthesized in good yields using a cheap and safe CO source [3].
Indole synthesis by reductive cyclization of ortho-nitrostyrenes: formate ester as CO surrogates / D. Formenti, F. Ferretti, F. Ragaini. ((Intervento presentato al 14. convegno Sigma-Aldrich Young Chemists Symposium tenutosi a Riccione nel 2014.
Indole synthesis by reductive cyclization of ortho-nitrostyrenes: formate ester as CO surrogates
D. FormentiPrimo
;F. FerrettiSecondo
;F. RagainiUltimo
2014
Abstract
The palladium catalyzed reductive cyclization of substituted ortho-nitrostyrenes is a powerful method for the synthesis of indoles. The reaction proceeds using CO as the reductant [1]. However CO is a highly toxic gas and its use implies the installation of expensive safety measures and high-pressure equipments. Therefore carbonylation reactions using non-gaseous CO precursors are highly desirable [2]. For our purpose we chose formate esters as the CO sources due their commercial availability and low cost. Thus, we developed a one-pot two-catalysts system composed of Ru3(CO)12 and [Pd(Phen)2][BF4]2 for the decarbonylation and the reductive cyclization step respectively. As the result various 2,6-substituted indoles were synthesized in good yields using a cheap and safe CO source [3].Pubblicazioni consigliate
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