An Alternative to the Classical α‐Arylation: The Transfer of an Intact 2‐Iodoaryl from ArI(O₂CCF₃)₂

Abstract

The α-arylation of carbonyl compounds is generally accomplished under basic conditions, both under metal catalysis and via aryl transfer from the diaryl λ(3)-iodanes. Here, we describe an alternative metal-free α-arylation using ArI(O2CCF3)2 as the source of a 2-iodoaryl group. The reaction is applicable to activated ketones, such as α-cyanoketones, and works with substituted aryliodanes. This formal C-H functionalization reaction is thought to proceed through a [3,3] rearrangement of an iodonium enolate. The final α-(2-iodoaryl)ketones are versatile synthetic building blocks.

The emergence of sulfoxide and iodonio-based redox arylation as a synthetic tool

“…Completing the last corner of the reactivity "square" shown in Figure 1, in a 2014 report Vallribera, Shafir and coworkers described a reaction between phenyliodine bis(trifluoroacetate), PIFA, and a range of activated ketones. 22 Under acidic conditions, such combination gave rise to α-arylketones with iodine retained ortho to the new C-C bond. The initial work involved the arylation of cyclic β-diketones and cyclic β-ketoesters, with the coupling products produced in moderate yields (Scheme 21).…”

“…Furthermore, the synthesis of the spiroxindole 84 from the α-(iodoaryl) ketones 74 (Scheme 24) relied on an intramolecular Cu-catalyzed Goldberg-type cyclizative C-N bond formation. 22 In 2015 Shafir et al showed that an intramecular cross-coupling can be combined with ring opening to give a series of interesting polar building blocks (Scheme 31). Thus, while basic treatment of the 5-membered cyclic dione 91 afforded the linear carboxylic acid 106 bearing a 2-iodophenyl substituent, conducting the same reaction in the presence of catalytic CuI/Fe2O3 led to a cross-coupling/ring opening sequence and a new benzophenone carboxylic acid 107.…”

Recent Developments in Inter- and Intramolecular Enolate Arylation

“…20 Cyclic b-ketoesters and b-diketones afforded the a-(2-iodoaryl) derivatives in moderate yields. Particularly efficient was the arylation of a-cyanoketones, tolerating even substituted iodoaryl derivatives.…”

α‐Arylation of Carbonyl Compounds through Oxidative C−C Bond Activation

“…[1,2] Prior to and following these advances,u seful transition-metal-free a-arylation processes have been developed that involve stoichiometric reactions of enolate anions (or equivalents) with electrophilic aromatic derivatives of Bi V , [3] Pb IV , [4] I(III), [5] S(IV), [6] or benzyne. [1,2] Prior to and following these advances,u seful transition-metal-free a-arylation processes have been developed that involve stoichiometric reactions of enolate anions (or equivalents) with electrophilic aromatic derivatives of Bi V , [3] Pb IV , [4] I(III), [5] S(IV), [6] or benzyne.…”