Síntesis de nitronas derivadas de aminoácidos y su aplicación en reacciones de tipo mannich

Resumo

In view of the widespread occurrence of nitrogenated compounds in Nature, and the recent demands for the synthesis of enantiomerically pure compounds, it is not surprising that stereoselective reactions on C=N systems are now considered one of the most important and fundamental approaches to nitrogen-containing products. In this work we focused our attention at the synthetic utility of nitrones when used as starting materials in i) Mannich-type reactions (a nucleophilic addition process) and ii) cycloaddition reactions of nitrone ylides; these reactions are completely different of typical 1,3-dipolar cycloadditions and lead to N-hydroxypyrrolidines. For these studies several types of nitrones, including those bearing oxygenated functionalities at the nitrogen atom were prepared. Preparation of the nitrones was carried out by using oxidation (from amines and hydroxylamines) and condensation (between hydroxylamines and aldehydes) methods. The investigations on Mannich-type reactions and cycloaddition reactions of nitrone ylides are described including theoretical approaches used for rationalizing the mechanism of the involved reactions.