Diaryliodonium Salts: A Journey from Obscurity to Fame

Abstract

The recent groundbreaking developments in the application of diaryliodonium salts in cross-coupling reactions has brought this class of previously underdeveloped reagents to the forefront of organic chemistry. With the advent of novel, facile, and efficient synthetic routes to these compounds, many more applications can be foreseen. Herein we provide an overview of the historical and recent advances in the synthesis and applications of diaryliodonium salts.

Formal Synthesis of (±)-Allocolchicine Via Gold-Catalysed Direct Arylation: Implication of Aryl Iodine(III) Oxidant in Catalyst Deactivation Pathways

“…Significantly greater catalyst deactivation was observed in this case, indicative of a link between a reaction of the starting material with PIFA and the catalyst deactivation process 3 . On the basis of steric hindrance and reduced electron density on the arene ring, diaryliodonium (22) generation would be expected to deactivate the trimethoxy-arene ring in aurated intermediates 23a-c to aromatic electrophilic substitution, [7] and thus prevent either the cyclisation to 24a-c, or reductive elimination of 24a-c, and thus prevent 3 See SI for full details.…”

“…In the case of electronrich arene substrates, replacing the "HCIB" oxidant (1), with "PIFA" (2) substantially reduced the rate of competing diaryliodonium salt formation [7], leading to greater yields of the desired C-C coupled cyclisation product. In the case of the cyclization of 3 to 4, where both the substrate and product bear a highly electron-rich trimethoxy benzene ring (Scheme 2), use of PIFA was essential.…”

Alkynylation with Hypervalent Iodine Reagents

“…Nevertheless, with the exceptions of the alkynylation of nitrogen and new applications in the synthesis of alkynyl metal complexes, most research on alkynyliodonium salts has concentrated in the year 1985-1995, with rare more recent breakthroughs. In particular, very few applications using modern catalytic methods have appeared, in stark contrast to the use of aryliodonium salts in arylation reactions [99]. One of the possible reasons for this "drying out" of the field is the relatively low stability of alkynyliodonium salts, which makes their use often challenging.…”

Chemoselectivity Investigation on Arylations Using Diaryliodonium Salts

“…2 They can be employed both in metal mediated and metal-free reactions thereby avoiding the potential drawbacks of organometallic chemistry such as toxicity and high cost. 3 Efficient one-pot procedures to diaryliodonium salts have been developed within our group (Scheme 1) increasing the availability of these compounds. With fast and non-expensive procedures for the preparation of these salts in hand we are currently investigating the electrophilic arylating potential of these reagents.…”