Preparation of nitrones and studies of their intramolecular 1,3-dipolar cycloaddition reactions

The importance of nitrones in synthetic organic chemistry has been widely illustrated 1 . The main reactions involving such compounds are nucleophilic addition and 1,3-dipolar cycloaddition (interand intramolecular) to olefins and acetylenes. A very important feature of the intramolecular 1,3-dipolar cycloaddition is that upto three continuous stereocentres can be introduced in a single step. These reactions have been used as an efficient method for the synthesis of isoxazolidine ring systems 1b,2 and as a key step in the synthesis of diverse target molecules containing nitrogen and oxygen 2c,3 . Isoxazolidines are becoming popular synthetic intermediates since they are prone towards selective cleavage of the NO bond under both reductive 4 and oxidative 5