Phosphine-free Heck reaction: mechanistic insights and catalysis "on water" using a charge-tagged palladium complex

Marcelo R. dos Santos, Romulo Coriolano, Marla N. Godoi, Adriano L. Monteiro, Heibbe C. B. de Oliveira, Marcos N. Eberlin, Brenno A. D. Neto
2014 New Journal of Chemistry  
A novel Pd-complex with a charge tag (imidazolium cation) was applied for online monitoring of the neutral Heck reaction by electrospray ionization (tandem) mass spectrometry -ESI-MS(/MS). The results shed light on the mechanism of the reaction, whereas the charge-tagged ligand also allowed the unprecedented MS monitoring of Pd 2+ reduction to Pd 0 . Key reaction intermediates associated with Pd catalysis could also be detected and characterized due to the presence of the charge tag on the
more » ... mplex. DFT calculations supported the proposed mechanism. The new charge-tagged Pd-complex is also shown to function as an active catalyst "on water" with the advantage of using cheaper and less reactive aryl chloride substrates in a phosphine-free version of the Heck reaction. Scheme 1 The basic neutral Heck reaction catalytic cycle.
doi:10.1039/c4nj00285g fatcat:xdfsmjhwcvb45i2gbrwaqcbguy