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–CH=CHPh and N2CHPh allowed us to isolate the organo- metallic 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 palla- dium-catalyzed cascade transformations of diazo derivatives leading to multiple C–C or C–X bond formation.