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 α-diazo-β-carbonylesters. In the crude decomposition mixtures, variable quantities of enamino-α,β-keto esters were detected as secondary products.