Stable chiral spirocyclic [5,5]-ammonium ylides using a metallo carbenoid approach

Enantiomerically pure spiro[5,5]-ammonium ylides were obtained by Rh(II)-catalyzed decomposition of alfa-diazo-beta-carbonylesters. In the crude decomposition mixtures, variable quantities of enamino-alfa,beta-keto esters were detected as secondary products.