Palladium-Catalyzed Formal Insertion of Carbenoids into Aminals via C–N Bond Activation

A new strategy for
selective insertion of metal carbenes into C–N
bond has been developed via Pd-catalyzed C–N bond activation.
A series of aminals and α-diazoesters with different substituents
were successfully incorporated even in 0.1 mol % of catalyst under
mild conditions, affording a wide range of α,β-diamino
acid esters with quarternary carbon-centers. Preliminary mechanistic
studies uncovered that the unique electrophilic cyclopalladated species
could easily react with diazoacetates to generate a Pd-carbenoid intermediate
which was involved in the catalytic cycle.