Two new polymer based catalysts, one manganese derived and the other iron derived have been prepared and characterised and successfully applied in the aziridination reaction. For the first time aziridination with Ho in the absence of any metal catalyst has been carried out. The latter reaction is shown to give selectively the trans product in the case of substituted olefins. The results from preliminary studies on asymmetric aziridination with several naturally occurring alkaloids are also discussed. (C) 2004 Elsevier B.V. All rights reserved.