Synthesis of 4-Methylbenzoate(2ʹ,4ʹ,6ʹ-trimethoxyphenyl) iodonium Tosylate

Hypervalent iodine continues to intrigue organic chemists with its diverse breadth of reactivity. The use of diaryliodonium salts as aryltransfer reagents has increased dramatically in the past decade as they have become more available by the development of efficient “one-pot” synthesis methods. Unsymmetrical diaryliodonium salts that selectively, and predictably, transfer one aryl group over the other are particularly desirable reagents, especially for the transfer of elaborate aryl groups to nucleophilic moieties. While the mesityl (Mes; 2,4,6-trimethylphenyl) group effectively serves as a general auxiliary in metal-catalyzed reactions of diaryliodonium salts, a broadly applicable auxiliary has not been adopted in metal-free reactions. Despite chemoselectivity studies that provide structural insight for auxiliary development few, if any, auxiliaries are in wide-spread use for metal-free nucleophile arylation reactions.8 We have been exploring the use of 2,4,6-trimethoxyphenyl (TMP) group as a spectator auxiliary of unsymmetrical aryl(TMP)iodonium salts toward this end and recently developed general one-pot syntheses of the tosylate and trifluoroacetate salts. On the basis of our continuing efforts to develop and promote the use of aryl(TMP)iodonium salts in metal-free aryl transfer reactions (equation 1), we describe here a decagram scale synthesis of one member in this class of reagent