posted on 2012-05-28, 00:00authored byAlberto Oviedo, Alma Arévalo, Marcos Flores-Alamo, Juventino J. García
The reactivity of Grignard reagents in the presence of
nickel catalysts is known to be highly efficient in the deoxydesulfurization
of dibenzothiophene sulfone (DBTO2), 4-methyldibenzothiophene
(4-MeDBTO2), and 4,6-dimethyldibenzothiophene (4,6-Me2DBTO2), to yield sulfur-free biphenyls via cross-coupling
reactions. However, the mechanistic details involved in the process
remained unknown. In this report the reactivity of [(dippe)Pt(μ-H)]2 with DBTO2 turned out to be catalytically less
efficient compared with [(dippe)Ni(μ-H)]2, but the
first allowed the isolation and full characterization of several reaction
intermediates, such as [(dippe)Pt(κ2-C,S-DBTO2)]. It was demonstrated that
this is a key intermediate in all the deoxydesulfurization reactions
of the above-mentioned aromatic sulfones (DBTsO2).