Pt(II)Cl 2 (DMSO) 2 -catalyzed cross-coupling of polyfluoroaryl imines Alex D. Sun, Jennifer A. Love * Department of Chemistry, 2036 Main Mall, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z1 1. Introduction The activation of carbon–fluorine bonds has been an active research area for more than 20 years. The challenge of activating C– F bonds has been overcome by numerous metal complexes and the results have been summarized in several reviews [1]. Up until recently, the research focus has been dominated by metal- mediated and metal-catalyzed hydrodefluorination reactions [2], resulting in reduction of the strong C–F bond. Such strategies have potential for use in fluorocarbon remediation. Over the last decade, considerable attention has been devoted to the selective activation and cross-coupling of polyfluorinated compounds [3–5]. Given the emergence of fluorine in bioactive molecules [6], such strategies have the potential for generating fluoroaromatic building blocks for use in pharmaceutical and industrial applications. In 2007, our group reported the first example of Pt-catalyzed cross-coupling of aryl fluorides. A range of polyfluoroaryl imines with different substitution patterns can be methylated in high yield and selectivity using [Pt 2 Me 4 (SMe 2 ) 2 ](1) and dimethylzinc, even in the presence of other potentially reactive functionalities [4a]. In a subsequent paper, we reported that the mechanism is consistent with the following steps (Scheme 1): (1) C–F oxidation addition of a low-valent, electron-rich Pt(II) complex to generate B; (2) transmetalation with dimethylzinc to generate C and (3) reductive elimination to furnish a Csp 2 –Csp 3 bond, regenerating the active catalyst A [4b]. Each Pt(IV) intermediate in the catalytic cycle was postulated to be a 5-coordinate species, based on the observation that additional SMe 2 decelerated each stoichiometric step, as well catalysis. Moreover, a 6-coordinate trimethyl Pt(IV) species formed (C-SMe 2 ) was thought to be a resting state for the catalytic cycle; this species can re-enter the cycle by dissociation of SMe 2 [4b]. We have also shown that the same precatalyst can be used in catalytic C–O bond formation, by a different (and as yet, undefined) mechanism [4c]. Although (1) is a highly efficient precatalyst, its low stability even under inert atmosphere at À30 8C makes it less than ideal for synthetic applications. In an effort to discover a more user-friendly precatalyst, we recently reported that PtCl 2 (SMe 2 ) 2 (2), a precursor of (1), is a viable as a air-, water- and thermal stable alternative to (1) [4d]. It is believed that (2) generates the active catalyst or some related species in situ by reacting with dimethylzinc. This precatalyst shares the same high selectivity and functional group tolerance as (1). However, although the practical advantage of using (2) is undoubtedly desirable, the major drawback it suffers is the lower reactivity compared to (1). With few exceptions, a significant decrease has been observed. Pre-treatment of (2) with dimethylzinc affords comparable activity to (1); however, this protocol is still less efficient than simply using (1). In order to further extend the utility of Pt(II)-catalyzed C–F cross-coupling, we sought to test related platinum(II) complexes. Journal of Fluorine Chemistry 131 (2010) 1237–1240 ARTICLE INFO Article history: Received 26 April 2010 Received in revised form 28 June 2010 Accepted 29 June 2010 Available online 6 July 2010 Keywords: Platinum(II) Polyfluoroarene Cross-coupling Dedicated to Professor Russell P. Hughes, Recipient of the 2010 ACS Award for Creative Work in Fluorine Chemistry. ABSTRACT PtCl 2 (DMSO) 2 has been identified as a readily accessible and effective C–F activation precatalyst. We report herein the study of reaction optimization and substrate scope. A comparison is made with previously reported [Pt 2 Me 4 (SMe 2 ) 2 ] and PtCl 2 (SMe 2 ) 2 precatalysts. ß 2010 Elsevier B.V. All rights reserved. * Corresponding author. Tel.: +1 6048223187; fax: +1 604822b3187. E-mail address: jenlove@chem.ubc.ca (J.A. Love). Contents lists available at ScienceDirect Journal of Fluorine Chemistry journal homepage: www.elsevier.com/locate/fluor 0022-1139/$ – see front matter ß 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jfluchem.2010.06.018