Palladium hydrazonato complexes and their role in the Pd-catalyzed cross-coupling reactions of hydrazones as carbene precursors

Autor: Francisco Villalba, Ana C. Albéniz
Rok vydání: 2022
Předmět:
Zdroj: Dalton Transactions. 51:17733-17742
ISSN: 1477-9234
1477-9226
DOI: 10.1039/d2dt03251a
Popis: Producción Científica
Hydrazones are common carbene precursors in many palladium-catalyzed cross coupling reactions of carbenes as a coupling partner, but their interaction with palladium has been overlooked. We have found that hydrazonato ligands readily coordinate to Pd aryl complexes leading to [Pd(Ar)(L-L){(TolSO2)N-N=CHR}] (Ar = Ph, C6F5; L-L = dppe, dppf; R = CH=CHPh, Ph). Ligand substitution reactions on [Pd(Ar)(dppe)X] (X = Br, TolSO2) show that the hydrazonato ligand coordinates preferently so the hydrazonato complexes are likely resting states in catalytic carbene coupling reactions using hydrazones as reactants. The decomposition of the hydrazonato moiety to a diazoalkane is needed during the catalysis and the analysis of the evolution of the hydrazonato complexes shows that it is not promoted by coordination to the metal and it does not occur in the coordination sphere of palladium. The substitution of diazoalkane for the metal-bound hydrazonato is possible and the steps that follow to form a new C-C bond, including the carbene migratory insertion, are fast.
MICINN (AEI, grant PID2019-111406GB-I00)
Junta de Castilla y León-FEDER (grant VA224P20)
MEC (FPU-17/04559 fellowship to F. V.)
Databáze: OpenAIRE