โ Scribed by Matthias Beller; Thomas H. Riermeier
No coin nor oath required. For personal study only.
Catalysis / Palladium / CฯชC coupling / Metallacycles / Trisubstituted olefins
The coupling reaction of 1,1-disubstituted olefins (ฮฑ-methyl-jor product. However, by using amines like Bu 3 N or diisopropylethylamine (DIPEA) as base internal olefins can be syn-styrene, n-butyl methacrylate) with various aryl bromides (Heck reaction) has been studied as a new concept to synthe-thesized with high selectivities. With phosphapalladacycle 3 as catalyst precursor, we were able to obtain catalyst turno-size trisubstituted olefins. Surprisingly, the nature of the base dramatically influences the product distribution. Thus, a sys-ver numbers up to 1000, while Pd(OAc) 2 /2PPh 3 was one order of magnitude less active. Analysis of the reaction profile tematic investigation on the role of base in Heck reactions of 1,1-disubstituted olefins was performed. Less coordinating by kinetic investigations led to the postulation of a reduction and subsequent oxidative addition of the catalyst precursor bases like NaOAc, NaOBz or Na 2 CO 3 yield a statistical distribution of regioisomers with the terminal olefin 10 as the ma-3 to form 12 as catalytically active intermediate.
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