- Stable N-heterocyclic carbene (NHC)-palladium(0) complexes as active catalysts for olefin cyclopropanation reactions with ethyl diazoacetate.
Stable N-heterocyclic carbene (NHC)-palladium(0) complexes as active catalysts for olefin cyclopropanation reactions with ethyl diazoacetate.
Chemistry (Weinheim an der Bergstrasse, Germany) (2011-12-06)
Carmen Martín, Francisco Molina, Eleuterio Alvarez, Tomás R Belderrain
PMID22139750
ABSTRACT
The Pd(0) complexes [(NHC)PdL(n)] (NHC=N-heterocyclic carbene ligand; L=styrene for n=2 or PR(3) for n=1) efficiently catalyse olefin cyclopropanation by using ethyl diazoacetate (EDA) as the carbene source with activities that improve on previously described catalytic systems based on this metal. Mechanistic studies have shown that all of these catalyst precursors deliver the same catalytic species in solution, that is, [(IPr)Pd(sty)], a 14e(-) unsaturated intermediate that further reacts with EDA to afford [(IPr)Pd(=CHCO(2)Et)(sty)], from which the cyclopropane is formed.
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