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Chen Beilstein J. The title compound was subjected to a nucleophilic aromatic substitution of the fluorine atom with oxygen, sulfur and nitrogen nucleophiles affording novel pentafluorosulfanyl benzenes with 3,5-disubstitution pattern. Vicarious nucleophilic substitution of the title compound with carbon, oxygen, and nitrogen nucleophiles provided 3-fluoronitro pentafluorosulfanyl benzenes substituted in position four.
Keywords: direct fluorination; fluorine; nucleophilic aromatic substitution; pentafluorosulfanyl group; vicarious nucleophilic substitution.
Organic compounds with a pentafluorosulfanyl SF 5 group are promising candidates in the development of new agrochemicals, pharmaceuticals and advanced materials . This is due to an unusual combination of properties such as high stability  , lipophilicity  and strong electron-withdrawing character  similar but more extreme than the trifluoromethyl group. Currently, the limiting factor for a more widespread use of SF 5 compounds is the low accessibility of basic building blocks and the lack of understanding their chemical behavior.
For aromatic SF 5 compounds, two main synthetic approaches exist. The first one is a direct fluorination of nitro-substituted diaryl disulfides leading to 3- or 4-nitro pentafluorosulfanyl benzenes . This reaction is conducted in tens of kilogram scale in industry. Fluorination in the second step affords arylsulfur pentafluorides [11,13]. However, nitro pentafluorosulfanyl benzenes are widely-available primary industrial products and starting materials to other SF 5 -benzenes which were prepared by reduction followed by condensation or diazotization chemistry [8,] , S E Ar  , S N Ar  , or metal-catalyzed cross-coupling reactions .
Synthetic methods to novel SF 5 -containing building blocks are sought after and drive the development of applications of these compounds. In this work, we explore S N Ar chemistry of 3-fluoronitro pentafluorosulfanyl benzene which was initially obtained as a minor byproduct of direct fluorination of 1,2-bis 3-nitrophenyl disulfane but can be also prepared by other methods, and show that substitution for aromatic fluorine or hydrogen atoms provide a range of novel structurally diverse SF 5 -benzenes.
However, for investigations of S N Ar of 2 , a more efficient process for its synthesis was required. With higher excess of fluorine, the 2 : 1 ratio increased. The reaction progress was monitored by GC analysis. When the direct fluorination was performed in anhydrous HF a markedly different result was obtained. However, in this case, higher amounts of byproducts, particularly difluoroderivatives 4 were observed. The amount of tar after the addition of 4.
Purification of compound 2 from 3 and 4 by distillation or column chromatography was not successful. Scheme 1: Direct fluorination of 1,2-bis 3-nitrophenyl disulfane. Scheme 2: Direct fluorination of 3-nitro pentafluorosulfanyl benzene 1. Scheme 3: Preparative fluorination of 3-nitro pentafluorosulfanyl benzene 1. Another method for the synthesis of 2 is the fluorodenitration of known 3,5-dinitro pentafluorosulfanyl benzene 5 [10,28].
Scheme 4: Synthesis of 2 by fluorodenitration of 5. Table 1: S N Ar reactions of 2. It is well known that ipso attack of nitroaromatics by nucleophiles S N Ar is only a secondary process. Under kinetic conditions the aromatic system is initially attacked by a nucleophile in ortho or para position to the nitro group, which was exploited in oxidative nucleophilic substitution for hydrogen reactions ONSH with organolithium or magnesium species or in vicarious nucleophilic substitution reactions VNS with carbon, oxygen or nitrogen nucleophiles . VNS is a very powerful process for selective alkylation, amination and hydroxylation of nitroaromatics and was reported to proceed efficiently on 1 and its para -isomer .
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Nucleophilic Aromatic Substitution - Chemistry LibreTexts
Rapid Commun. Long, T. Katz, J. Single-step synthesis of D 3h -symmetric bicyclooxacalixarenes.
Alsbaiee, A. Nature , — Xiao, L. Wu, Z. Russian Chemical Bulletin. Analysis of many variants of nucleophilic aromatic substitution of hydrogen proceeding according to an addition—elimination pattern reveals that this is the major reaction pathway, whereas nucleophilic replacement of halogen or another nucleofugal group is the secondary process, i.
In this respect electrophilic and nucleophilic aromatic substitution can be considered as analogous processes. Unable to display preview. Download preview PDF. Skip to main content. Advertisement Hide.
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Electrophilic and nucleophilic aromatic substitution: Analogous and complementary processes. Authors Authors and affiliations M. This is a preview of subscription content, log in to check access.
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