(omega-ammonioalkyl)cyclopentadienides by rhodium-catalyzed vinylcarbene transfer to semicyclic enaminocarbonyl compounds

The rhodium(ll) catalyzed reaction of vinyldiazoacetate 2 with semicyclic b eta-enaminocarbonyl compounds 1 provides (omega-(methylammonio)-alkyl)cyclo pentadienides 3. This transformation represents a novel reaction cascade wh ich combines carbenoid addition at a C=C bond with ring chain transformatio n. In some cases, products resulting from vinylcarbene insertion into the e naminic C-H bond of 1 are also isolated, These dienamines undergo subsequen t isomerization to furnish betaines 3.