Synthesis of Polycyclic Nitrogen Heterocycles via Alkene Aminopalladation/Carbopalladation Cascade Reactions

A new method for the synthesis of tricyclic nitrogen heterocycles from N,2-diallylaniline derivatives is described. These transformations proceed via sequential alkene aminopalladation of an intermediate L_nPd(Ar)(NRR′) species followed by alkene carbopalladation of the resulting L_nPd(Ar)(R) complex. Both alkene insertion steps occur in preference to C−N or C−C bond-forming reductive elimination. An unusual 1,3-palladium shift occurs when 2-Allyl-N-(2-vinylphenyl)aniline is employed as substrate, which yields a tetracyclic molecule with three contiguous stereocenters.