Insight into the Mechanism of Platinum-Catalyzed Cross-Coupling of Polyfluoroaryl Imines

Abstract

We recently reported the first examples of Pt-catalyzed methylation of polyfluorinated arenes as a means to generate partially fluorinated aromatic building blocks. The reaction is selective for cleavage of C-F bonds ortho to an imine substituent and allows for preferential cleavage of C-F bonds in the presence of considerably weaker bonds (e.g., C-Br). We report herein the proposed mechanism for this reaction. Initial C-F activation generates a Pt(IV)-F intermediate, which then reacts with (CH 3 ) 2 Zn via transmetalation. Subsequent reductive elimination from the Pt(IV) species generates a new sp 2 -sp 3 C-C bond. In addition, we have identified a species present during the catalytic reaction and propose this to be the catalyst resting state.

Fluorine as a ligand substituent in organometallic chemistry: A second chance and a second research career

“…Much of this recent activity is driven by the need for synthetic procedures to incorporate fluorine or a CF 3 group strategically in the synthesis of pharmaceuticals or PET reagents, leading to the development of new methodology for formation of C-F and C-CF 3 bonds [110][111][112][113][114][115][116][117][118][119][120][121][122]. Organometallic chemistry involving the chemical functionalization of C-F bonds also continues to be an active field [123][124][125][126][127][128][129][130][131][132][133][134][135][136].…”

Catalytic Enantioselective Cyclization and C3-Fluorination of Polyenes

“…Neither the [Pt] IV nor the [Pt]-H species are observable by NMR, however, literature precedence suggests that both routes are viable. 17,5d,5f,5i,5k …”

Carbon–Carbon Bond Forming Reactions Mediated by Organozinc Reagents

“…The mechanism involves the activation of the C-F bond ortho to the imine by oxidative addition to provide a Pt(IV)-F intermediate. methylated arene closes the catalytic cycle [307]. The procedure is highly selective as illustrated by the coupling of 453 that leaves the weaker carbon-bromine bond intact.…”