Electrophilic Triflyl-arylation and Triflyl-pyridylation by Unsymmetrical Aryl/Pyridyl-λ³-iodonium Salts: Synthesis of Aryl and Pyridyl Triflones

Abstract

Unsymmetrical diaryl-λ-iodonium salts containing aryl triflone (Ar-SOCF) were designed and synthesized. X-ray crystal structure analysis of the salt indicated a T-shaped geometry at the iodine atom. The salts were found to be powerful electrophilic reagents for triflyl-arylation of C-, N-, and O-centered nucleophiles under mild conditions. Electrophilic transfer of pyridine triflone (Py-SOCF) to nucleophiles was also realized by the use of corresponding triflylpyridyl-aryl-λ-iodonium salts. Selection of auxiliaries (dummy ligands) of unsymmetrical diaryl-λ-iodonium salts is crucial for this transformation.

Synthesis of fluoro-functionalized diaryl-λ3-iodonium salts and their cytotoxicity against human lymphoma U937 cells

“…We will continue the biological investigation of 3 in this direction. From the view point of organic synthesis, the newly synthesized ortho -SF 5 -substituted unsymmetrical iodonium salts 3p , 4b , 5a and 6a have potential use as electrophilic SF 5 -phenylation reagents for a range of nucleophiles such as alcohols, amines, thiols, and active methylene nucleophiles [ 59 – 61 ]. The application of these ortho -SF 5 -substituted diaryliodonium salts in organic synthesis, as well as their detailed bioactive behaviour, will be reported in due course.…”

The C3-H Bond Functionalization of Quinoxalin-2(1H)-Ones With Hypervalent Iodine(III) Reagents

“…Among these significant works, hypervalent iodine reagents have been widely used as ideal and highly efficient oxidants or reaction partners (Kita et al, 1994 ; Nasrallah et al, 2019 ) due to their superior bench stability, high reactivity, low toxicity, environmental friendliness, ease of operation, and ready availability (Dohi et al, 2009 ; Sun and Shi, 2014 ). For instance, diverse iodine(III) reagents were invented to introduce fluorinated group into organic molecules (Yang et al, 2013 ; Matsuzaki et al, 2014 ; Suzuki et al, 2014 ; Das and Shibata, 2017 ; Das et al, 2017 ; Wang et al, 2017 ). Because of the large size of iodine atoms, a linear three-center, four-electron (3c-4e) bond (L–I–L) which uses a non-hybridized 5p orbital of iodine atom is formed.…”

Anionic Triflyldiazomethane: Generation and Its Application for Synthesis of Pyrazole-3-triflones via [3 + 2] Cycloaddition Reaction

“…Recently, heteroatom-linked CF 3 variants, i.e., XCF 3 , including trifluoromethoxy (OCF 3 ), trifluoromethylthio (SCF 3 ), and trifluoromethanesulfonyl (triflyl, SO 2 CF 3 ), , have gained attention. In particular, we are interested in the SO 2 CF 3 compounds (triflones) − because of their high electron-withdrawing ability and mild lipophilicity of SO 2 CF 3 (σ m = 0.79, σ p = 0.93; π = 0.55) compared to CF 3 . Numerous triflones have been reported, even though compounds with an SO 2 CF 3 on the heterocyclic ring, i.e., heterocyclic triflones, are rather limited .…”

“…In particular, we are interested in the SO 2 CF 3 compounds (triflones) − because of their high electron-withdrawing ability and mild lipophilicity of SO 2 CF 3 (σ m = 0.79, σ p = 0.93; π = 0.55) compared to CF 3 . Numerous triflones have been reported, even though compounds with an SO 2 CF 3 on the heterocyclic ring, i.e., heterocyclic triflones, are rather limited . Our group has been engaged for decades in the development of shelf-stable reagents for fluoro-functionalization reactions such as fluorination, trifluoromethylation, and trifluoromethylthiolation reactions .…”

“…Multiply substituted β-lactam triflones are also accessed by the reaction of ketene triflone with imines via the Staudinger [2 + 2] cycloaddition reaction (Scheme d) . As an extension of our research work on heterocyclic triflones, , we herein report the synthesis of pyrazole triflones 3 by the reaction of 1a with nitroalkenes 2 under basic conditions (Scheme e). Nitroalkenes 2 bearing electron-withdrawing, electron-donating, or halogenyl substituents on the aryl ring gave the desired pyrazole triflones 3 in good to high yields almost independent of their substitution and positions.…”