2017
DOI: 10.1002/slct.201601735
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Tri–tert‐Butanolamine as an Organic Promoter in Nucleophilic Fluorination

Abstract: Tri-tert-butanol amine acts as promoter with alkali metal salts in the nucleophilic fluorination of alkylsulfonates. It significantly enhances the reactivity of alkali metal salts with minimum formation of side-products (alkene, ether, and alcohol) com-pared to other catalysts in fluorination reaction. The synergism of tert-alcohol and amine moiety plays a pivotal role in fluorination.

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Cited by 20 publications
(40 citation statements)
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“…From the discussions above we proposed that using F − or OMs − as the counter‐anion render the S N Ar fluorination process to be strongly favorable over the side reactions. Further enhancement of rates of fluorination may still be possible by employing Lewis base promoters such as crown ethers, which proved to be phenomenally efficient agents for promoting S N 2 fluorination [ 5,7,28–31 ] : The electronegative O atoms in a crown ether would strongly interact with the counter‐cation Cs + to suppress its retarding Coulombic influence on the nucleophile F − , thereby “freeing” the latter for better reactivity. On the other hand, the amino group may not much be affected by the crown ether; thus, selective acceleration of fluorination would be achieved.…”
Section: Resultsmentioning
confidence: 99%
“…From the discussions above we proposed that using F − or OMs − as the counter‐anion render the S N Ar fluorination process to be strongly favorable over the side reactions. Further enhancement of rates of fluorination may still be possible by employing Lewis base promoters such as crown ethers, which proved to be phenomenally efficient agents for promoting S N 2 fluorination [ 5,7,28–31 ] : The electronegative O atoms in a crown ether would strongly interact with the counter‐cation Cs + to suppress its retarding Coulombic influence on the nucleophile F − , thereby “freeing” the latter for better reactivity. On the other hand, the amino group may not much be affected by the crown ether; thus, selective acceleration of fluorination would be achieved.…”
Section: Resultsmentioning
confidence: 99%
“…The intricate interplay (Coulombic forces) of the counter-cation, the nucleophile, IL cation and anion helps to form a pre-reaction complex and transition state that is optimal for S N 2 fluorination, prohibiting the formation of by-products (Figure 1). The role of IL anion in this mechanism corresponds to that of electronegative O atoms in oligoethylene glycols [36] or in bulky alcohols [37][38][39] (t-butanol and amyl alcohol) that were proved to act as catalyst/promoter in nucleophilic fluorination, but were probably better because of the explicit negative charge of IL anions. Magnier and coworkers [40] carried out a somewhat different approach to using ILs for nucleophilic fluorination.…”
Section: S N 2 Fluorination In Ionic Liquidsmentioning
confidence: 97%
“…[36] They chose the fluorination of 30 as model reaction; when 18-crown-6 was utilized as promoter in MeCN, a low yield 46 % of the desired fluorinated product 31, along with 8 % alkene 32, were observed. However, when the specially designed tert -butanol amines were subjected to the reaction, both the yield and selectivity towards 31 increased dramatically.…”
Section: Hydrogen Bonding Controlled Nucleophilic Fluorination By Alkmentioning
confidence: 99%
“…Shinde and co‐workers disclosed that the alkylamine bearing t BuOH moiety could also function as promoter for a highly selective fluorination using CsF as nucleophilic source (Scheme ) . They chose the fluorination of 30 as model reaction; when 18‐crown‐6 was utilized as promoter in MeCN, a low yield 46 % of the desired fluorinated product 31 , along with 8 % alkene 32 , were observed.…”
Section: Hydrogen Bonding Controlled Nucleophilic Fluorination By Alkmentioning
confidence: 99%