Water-compatible one-pot organocatalytic asymmetric synthesis of cyclic nitrones. Application in intramolecular 1,3-dipolar cycloadditions

Optically active five-membered cyclic nitrones are readily obtained in a one-pot procedure via the organocatalytic Michael addition of aldehydes to nitroolefins and in situ reductive cyclization. Application of the methodology to the synthesis of tricyclic compounds through intramolecular 1,3-dipolar cycloaddition reactions (DFT calculations have also been performed) is also demonstrated. All the reactions were carried out in water as a solvent and excellent ee values (ee >99%) were obtained. (C) 2011 Elsevier Ltd. All rights reserved.