UBC Theses and Dissertations
Selective, catalytic C-F activation as a route to methyl- and ether- punctionalized polyfluoroarylimines Buckley, Heather Louisa
Platinum (II) complexes were used to achieve catalytic C-F bond activation and cross-coupling of a series of polyfluoroarylimines. PtCl₂(SMe₂)₂ (21) was found to be active for coupling to obtain Ar-CH₃ bonds, a reaction which had been previously reported using Pt₂Me₄(SMe₂)₂ (1) as a catalyst. The yields of the two reactions are comparable, and 21 is a significantly easier compound to prepare. This reaction is postulated to have a similar reaction mechanism to that determined for the C-C cross-coupling achieved using 1. In addition, a new example of cross-coupling of a polyfluoroarylimine not possessing a 2,6-difluorination pattern (imine 26) was demonstrated. Platinum complex 1 was demonstrated to be active for a new catalytic cross-coupling reaction to generate aryl methyl ethers from the same series of polyfluoroarylimines. The imine products were characterized by ¹H and ¹⁹F NMR spectroscopy, and their corresponding aldehydes were fully isolated and characterized by ¹H, ¹³3C and ¹⁹F NMR spectroscopy and elemental analysis. The structure of aldehyde 46 was further confirmed by X-ray crystallography. The substrate limitations of this reaction are greater, with electron withdrawing groups required at the 2, 4, and 6 positions. A preliminary mechanistic investigation revealed that the mechanism is different from that reported for the corresponding C-C cross-coupling reaction, but that the platinum catalyst is required and the reaction does not proceed through a traditional organic chemistry mechanism. This reaction may be the first example of catalytic C-O reductive elimination from a platinum (IV) centre.
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