Diazo compounds and palladium–aryl complexes: trapping the elusive carbene migratory insertion organometallic products

Abstract

The reactions of Pd–aryl complexes with diazo compounds N₂CH–CHCHPh and N₂CHPh allowed us to isolate the organometallic products formed right after the migratory insertion of a non-stabilized CHR carbene into the Pd–aryl bond. η³-Allylic and η³-benzylic palladium complexes were formed respectively. This is compelling experimental evidence for the key step in the palladium-catalyzed cascade transformations of diazo derivatives leading to multiple C–C or C–X bond formation.