The reaction of 2,3-butanedione, ethyl pyruvate and phenylglyoxal with β-nitrostyrene and L-proline in isopropanol at room temperature gives substituted pyrrolizidines, as a result of one-pot three component reaction.On the contrary, a spiropyrrolizidine is formed from 1,2-cyclohexanedioneonly when the reaction is carried out in refluxing isopropanol, whereas at room temperature, incorporation of the amine component into the products is not observed and bicyclo[3.2.1]octanones are formed, as a result of atandem Michael-Henry reaction. In this latter case L-proline acts as an organocatalyst, although with modest enantioselectivity. Thestereochemistry of the products is given and the mechanism of formation of products is postulated, on the basis of stereochemical arguments.

Application of 1,3-azomethine ylides derived from alfa-dicarbonyl compounds and L-proline to the synthesis of pyrrolizidines

FELLUGA, FULVIA;FORZATO, Cristina;NITTI, PATRIZIA;PITACCO, GIULIANA;VALENTIN, ENNIO;ZANGRANDO, ENNIO
2010-01-01

Abstract

The reaction of 2,3-butanedione, ethyl pyruvate and phenylglyoxal with β-nitrostyrene and L-proline in isopropanol at room temperature gives substituted pyrrolizidines, as a result of one-pot three component reaction.On the contrary, a spiropyrrolizidine is formed from 1,2-cyclohexanedioneonly when the reaction is carried out in refluxing isopropanol, whereas at room temperature, incorporation of the amine component into the products is not observed and bicyclo[3.2.1]octanones are formed, as a result of atandem Michael-Henry reaction. In this latter case L-proline acts as an organocatalyst, although with modest enantioselectivity. Thestereochemistry of the products is given and the mechanism of formation of products is postulated, on the basis of stereochemical arguments.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2296162
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