899795-71-2Relevant academic research and scientific papers
Unusual anion effects in the iron-catalyzed formation of 3-hydroxyacrylates from aromatic aldehydes and ethyl diazoacetate
Alves, Luis Goncalo,Dazinger, Georg,Veiros, Luis F.,Kirchner, Karl
experimental part, p. 3160 - 3166 (2011/01/05)
Due to the lability of one of the CO ligands in irans-[Fe(PNP)(CO) 2Cl]+ this compound is an efficient catalyst for the coupling of a series of aromatic aldehydes with ethyl diazoacetate (EDA), which give, in most cases, selectively 3-hydroxyacrylates rather than β-oxo esters. This reaction is strongly dependent on the nature of the counterion, Whereas with BF4- the reaction proceeds with conversions up to 90%, in the case of the counterions NO3-, CF 3COO-, CF3SO3-, SbF 6-, and BAr'4- [Ar' = 3,5-(CF 3)2C6H3] no reaction took place. In the case of PF6- only up to 20% conversion was achieved. A conceivable mechanism for the coupling of aromatic aldehydes with EDA was established by means of DFT/B3LYP calculations, which allowed the rationalization of both the chemoselectivity and the role of the counterions.
