Synthesis of Cyclic and Acyclicortho‐Aryloxy Diaryliodonium Salts for Chemoselective Functionalizations

Abstract

Two regioselective, high-yielding one-pot routes to oxygen-bridged cyclic diaryliodonium salts and ortho-aryloxysubstituted acyclic diaryliodonium salts are presented. Starting from easily available ortho-iodo diaryl ethers, complete selectivity in formation of either the cyclic or acyclic product could be achieved by varying the reaction conditions. The complimentary reactivities of these novel ortho-oxygenated iodonium salts were demonstrated through a series of chemoselective arylations under metal-catalyzed and metalfree conditions, to deliver a range of novel, ortho-functionalized diaryl ether derivatives.

Site Selective Concerted Nucleophilic Aromatic Substitutions of Azole‐Ligated Diaryliodonium Salts

“…A selective nitration of unsymmetrical diaryliodonium salts has been reported. Here, electronic factors were more important, and nitration of electron‐deficient aryl moieties predominated [15a–b,f] . Other studies have noted a strong influence of the ortho ‐effect on the chemoselectivity of ortho ‐substituted iodonium salts, despite competing electronic preferences [15c–e] .…”

Ligand-free Ullmann-type arylation of oxazolidinones by diaryliodonium salts

“…Further optimization revealed that the change from Et 3 N to inorganic bases was also not beneficial (entries 12 and 13). The addition of pyridine or its derivatives resulted in a drastically reduced yield (up to 11%; Table 1, entries [12][13][14][15][16][17]. We also varied the type of copper catalysts and found that both the change of the counter anion and the oxidation state led to a lower yield of 3a (entries 18-21).…”

“…12 However, the main application of diaryliodonium salts is still related to their ability to arylate a variety of nucleophiles (C, N, P, S, halogens, etc.). 1,2,[13][14][15][16][17][18] The use of diaryliodonium salts in the arylation of N-containing heterocyclic systems is particularly attractive, especially because of their ubiquitous application in drug development. Reactions with electron-rich heterocycles succeed under mild conditions without the addition of transition metal-based catalysts.…”

“…12 However, the main application of diaryliodonium salts is still related to their ability to arylate a variety of nucleophiles (C, N, P, S, halogens, etc .). 1,2,13–18…”

Synthesis of Complex Diarylamines through a Ring‐Opening Difunctionalization Strategy**

“…The retained iodo substituent [15] is well suited for further derivatizations. [14,16] This strategy allows transformations of inexpensive and readily accessible cyclic amines into linear diarylamines with two structurally diverse N-aryl groups as well as various new polar functionalities at the carbon chain. Such complex products were inaccessible through our previous diarylation of primary amines (Scheme 1B) [14a] as formation of the required primary amine nucleophiles would require multistep synthesis, and reactions with unprotected polar-or oxidation sensitive functionalities on the amines often resulted in decomposition.…”