Stereochemistry and nmr Spectra of Some Tricyclic Condensed Thiazolidine Derivatives with a Bridgehead Nitrogen Atom

Abstract

The configuration of a series of tricyclic condensed thiazolidines with a bridgehead nitrogen atom, for which erroneous data had been published, was determined by X-ray structural analysis and NMR spectroscopy.The addition of thiiranes at the C=N double bond of azomethines provides a convenient method for the preparation of thiazolidines [1, 2]. The mechanism of the reaction involves opening of the thiirane ring by an imine or α-ethoxyamine (if ethanol is present in the reaction mixture) and is accompanied by inversion of the configuration of the attacked carbon atom of the thiirane [2]. This method of synthesis of thiazolidines is particularly effective in the case of cyclic imines in that it opens up the simple possibility for synthesis of bicyclic condensed derivatives with a nitrogen atom at the bridgehead position or their analogs with a larger number of rings [1,3,4].