eesti teaduste
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of the estonian academy of sciences
ISSN 1736-7530 (Electronic)
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Computational study of the copper-free Sonogashira cross-coupling reaction: shortcuts in the mechanism; pp. 133–140
PDF | doi: 10.3176/proc.2013.2.07

Lauri Sikk, Jaana Tammiku-Taul, Peeter Burk

The sec-butylammonium salt catalysed oxidative addition of phenyl bromide to tris(triphenylphosphane)palladium and reaction of phenylacetylene with cis-Pd(PPh3)2(Ph)Br were modelled using DFT B97D/cc-pVDZ method to study the mechanism of the copper-free Sonogashira cross-coupling reaction. sec-Butylammonium bromide influences the oxidative addition by coordinating with palladium catalyst and the resulting product is trans-Pd(PPh3)2(Ph)Br, not the corresponding cis-compound, which is formed in the absence of salt. The transition-state energy of this oxidative addition mechanism is very close to the previously reported biligated oxidative addition pathway. Reaction of acetylene with cis-Pd(PPh3)2(Ph)Br can lead to either a trans- or a cis-Pd(PPh3)2(CCPh)Ph complex, while only the latter is capable of undergoing reductive elimination.


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