Markovnikov at Gold: Nucleophilic Addition to Alkenes at Au(III)

Abstract

The reactivity of Au(OAc F ) 2 (tpy) (1, OAc F = OCOCF 3 ; tpy = 2-(p-tolyl)pyridine) toward a wide variety of different alkenes with various substitution patterns and different oxygen-based nucleophiles has been investigated. These reactions are two-step processes where a ligand substitution is followed by a nucleophilic addition furnishing Au(III) complexes with C(sp 3 ) ligands. In this work we have found that the reactions always occur trans to tpy-N while the OAc F ligand remains in place trans to tpy-C. The nucleophilic addition takes place exclusively at the most substituted side of the double bond, in a Markovnikov manner, and the nucleophilic addition occurs in an anti fashion as can be seen from the reaction with the 2,3-disubstituted alkene trans-2-hexene. This study has provided valuable insight into the scope and regiochemistry of Au(III) mediated nucleophilic additions, which is of great importance for further development of Au(III) catalysis and alkene functionalization.

Synthesis of substituted (N,C) and (N,C,C) Au(iii) complexes: the influence of sterics and electronics on cyclometalation reactions

“…The bond angles are similar to those previously reported for structurally related square planar Au(III) complexes. 19,21,26,29 The Au1-N1 and Au1-C7 bond lengths are in the range of 1.9974 (19)-2.0426(17) Å and 1.988(2)-2.02(2) Å, being comparable to those reported for 2a-Au(OAc F ) 2 (1.991(6) Å and 1.995(7) Å, respectively). 19 The Au1-O3 (trans to N) bond lengths are in the range of 2.0032(16)-2.034(3) Å, all being slightly longer than the corresponding bond length in 2a-Au(OAc F ) 2 (1.993(5) Å).…”

“…1). The reactivity of 2a-Au(OAc F ) 2 towards organolithium and Grignard reagents, 19,20 ethylene, 24,25 higher alkenes 26 and acetylene 7 has since then been explored. Subsequent to the initial findings, only few examples of trifluoroacetate complexes of Au (III) with 2-arylpyridine ligands have been reported.…”

Do Gold(III) Complexes Form Hydrogen Bonds? An Exploration of AuIII Dicarboranyl Chemistry

“…Even the addition of an excess of NnBu 4 Cl in dichloromethane at room temperature displaced only the triflate to give the chloro complex 3,w hilet he 2-phenylpyridine ligand was retained.L ike 2,c omplex 3 is stable to water and air.T he reaction illustrates the electron-withdrawing properties of the dicarboranyl ligand,w hichi ncreases the Lewis acidity of the gold(III) centre. Whereas aryl-typec arbanions, for example, in the 2-phenylpyridine C^N chelate, exert as trong trans influence and facilitate ligand substitution, [34][35][36] this effect is evidently much weaker for C-bound dicarboranyl ligands.…”

Synthesis, Characterization, and Reactivity of Cyclometalated Gold(III) Dihalide Complexes in Aqua Regia

“…Interestingly, Roth and Blum have reported that that kinetic basicities of Au(I)-C bonds increase somewhat in the order sp 3 < sp < sp 2 . [37] We have reported that ethylene [38] and other alkenes [39] undergo formal insertion into one Au-OAc F bond in Au(tpy)(OAc F ) 2 (tpy = p-tolylpyridine, an N^C chelating ligand; see Scheme 1a) in trifluoroacetic acid. These reactions proceed via an alkene coordination-nucleophilic attack mechanism and occurs selectively at the coordination site trans to pyridine-N of the tpy ligand.…”