67696-28-0Relevant academic research and scientific papers
Expedient and efficient one pot synthesis of trifluoroethyl ethers from metal free 2,4,6-tris-(2,2,2-trifluoro-ethoxy)-[1,3,5] triazene
Mangawa, Shrawan Kumar,Sharma, Chiranjeev,Singh, Ashawani Kumar,Awasthi, Satish K.
, p. 35042 - 35045 (2015/05/04)
An efficient synthesis of fluorinated alkyl and aryl ethers was achieved by the use of s-triazene derived fluorinated reagent 2,4,6-tris-(2,2,2-trifluoro-ethoxy)-[1,3,5] triazene (TriTFET). The procedure offers a very attractive alternative for the synthesis of fluorinated motifs that are found in various bioactive molecules. Moreover, TriTFET is a synthetic non-toxic, non-ozone depleting and stable reagent. All compounds were characterized by 1H, 13C and 19F NMR.
Base mediated deprotection strategies for trifluoroethyl (TFE) ethers, a new alcohol protecting group
Yang, Qingliang,Njardarson, Jon T.
supporting information, p. 7080 - 7082 (2013/12/04)
A trifluoroethyl (TFE) ether is specifically introduced as a protecting group in organic chemistry. Its first strategic application and removal in the total synthesis of vinigrol is discussed. Two lithium base mediated deprotection strategies for its removal are presented in this Letter. In one deprotection approach, the trifluoroethyl ether is converted to a difluorovinyl ether and then catalytically cleaved using osmium tetraoxide, while in the second approach a difluorovinyl anion is formed and trapped with an electrophilic oxygen reagent (MoOPH) to form a labile difluoroacetate. To further aid the reader, a summary of approaches for forming trifluoroethyl ethers is included as well as a discussion of alternate deprotection strategies.
A simple, rapid procedure for nucleophilic radiosynthesis of aliphatic [18F]trifluoromethyl groups
Riss, Patrick J.,Aigbirhio, Franklin I.
supporting information; experimental part, p. 11873 - 11875 (2011/12/04)
A procedure for the radiosynthesis of aliphatic [18F] trifluoromethyl groups by reacting 1,1-difluorovinyl precursors with [ 18F]fluoride ions, resulting in the equivalent of direct nucleophilic addition of H[18F]F, has been developed. A variety of 18F-labelled model compounds were then obtained and two potential [18F]radiotracers were synthesised by a two step process starting from 1,1-difluorovin-2-yl 4-toluenesulfonate. The method is widely applicable for the synthesis of novel radiotracers in high radiochemical yields and good specific activity.
Facile allylboration of ketones with β-benzyloxy-γ,γ-difluoroallylboronate: Preparation of gem-difluorinated homoallylic tert-alcohols
Ramachandran, P. Veeraraghavan,Chatterjee, Anamitra
experimental part, p. 144 - 150 (2009/07/18)
The reaction of β-benzyloxy-γ,γ-difluoroallylboronate, at room temperature and in the absence of catalysts, with a variety of aromatic and aliphatic ketones of varying sterics and electronic requirements furnishes fluorinated homoallylic tert-alcohols in
Gem-difluorinated homoallyl alcohols, β-hydroxy ketones, and syn- and anti-1, 3-diols via γ,γ-difiuoroallylboronates
Ramachandran, P. Veeraraghavan,Chatterjee, Anamitra
supporting information; experimental part, p. 1195 - 1198 (2009/04/07)
γ,γ-Difluoroallylboronates have been prepared from trifluoroethanol and utilized for the allylboration of a variety of aldehydes to provide gem-difluorinated homoallylic alcohols. α-Chiral aldehydes were allylborated in 4:1-13:1 diastereoselectivity favoring the anti-isomer. A representative series of difluorinated hydroxyl enol ethers were converted to the corresponding α, α-difluoro-β-hydroxy ketones. Diastereoselective reduction of one of these to either syn- and anti-1,3-diol was also studied.
Rate and product studies with benzyl and p-nitrobenzyl chloroformates under solvolytic conditions
Kyong,Park,Kim,Kevill
, p. 8051 - 8058 (2007/10/03)
The specific rates of solvolysis of p-nitrobenzyl chloroformate are well correlated using the extended Grunwald-Winstein equation, with a high sensitivity (l) to changes in solvent nucleophilicity (N(T)) and a moderate sensitivity (m) to changes in solvent ionizing power (Y(Cl)). The values are consistent with a rate-determining association within an association-dissociation pathway. The selectivity values (S) for the attack at the acyl carbon show a modest preference for ethanol over water and a relatively high preference for ethanol over 2,2,2-trifluoroethanol (TFE). The solvolyses of benzyl chloroformate show similar characteristics in solvents of relatively high nucleophilicity and/or low ionizing power. In solvents with considerable fluoro alcohol content, an ionization mechanism, accompanied by loss of carbon dioxide, leads to benzyl chloride, benzyl alcohol, and benzyl alkyl ether. A new correlation now applies, with a much lower l value and somewhat higher m value. The S values for this pathway are close to unity, even in TFE-ethanol mixtures, consistent with the components of the binary solvent capturing a highly reactive carbocation.
Chemoselective reaction of a sulfonate ester with methoxide ions in preference to benzyl mercaptide anions
Langler, Richard Francis,Morrison, Nancy Ann
, p. 2385 - 2389 (2007/10/02)
Trifluoroethyl benzyl sulfide was prepared (in 2-propanol) and subsequently chlorinated as a further test of substituent electronegativity based regiochemical predictions.The initial attempt to prepare that sulfide by reaction of 2,2,2-trifluoroethyl methanesulfonate and benzyl mercaptide anions (in methanol) furnished benzyl methyl sulfide.Mechanistic possibilities are discussed in detail and some synthetic consequences of this novel reaction are presented.
Solvolysis of Benzyl Azoxytosylate and the Effect of Added Bases and Nucleophiles in Aqueous Trifluoroethanol and Aqueous Acetonitrile
Maskill, H.,Jencks, William P.
, p. 2062 - 2070 (2007/10/02)
The rates and products of reaction of benzyl azoxytosylate (1b) in 1:1 (v/v) aqueous trifluoroethanol containing sodium perchlorate, sodium thiocyanate, sodium iodide, sodium bromide, sodium chloride, sodium hydroxide, sodium acetate, perchloric acid, and imidazole (buffered and unbuffered) have been measured at 42 deg C as part of an investigation into its mechanism of solvolysis.Nonbasic solutes give only small rate effects (some rate enhancing, others rate retarding), but, if nucleophilic, they lead to substitution products-the classic evidence of an SN1 reaction mechanism.After the initial rate-determining fragmentation, about half of the total solvolytic reaction proceeds through an electrophilic benzylic intermediate which is sufficiently long-lived to be trapped by nucleophilic solutes such as thiocyanate and the halide anions to give benzyl thiocyanate and benzyl halides.The other half gives the solvent-derived products benzyl alcohol and benzyl trifluoroethyl ether by a route which is not affected by dilute nonbasic solutes.Sodium acetate, which leads to negligible formation of benzyl acetate, and imidazole lead to the formation of trifluoroethyl tosylate; imidazole also produces N-tosylimidazole.These two base-induced bimolecular reactions involve nucleophilic attack at the sulfur of the tosyl group and involve electronic polarization of 1b in the opposite sense from that in the unimolecular fragmentation.One of the minor products in the presence of bases from the trappable intermediate of the solvolysis reaction is benzaldehyde, which suggests that the intermediate is C6H5CH2ON2+, a new type of reactive electrophile.It is not yet certain whether the half of the unimolecular fragmentation reaction which does not proceed through the trappable intermediate involves another electrophilic intermediate which is simply too short-lived to be intercepted by dilute nucleophiles or whether about half of the initial fragmentation is followed by a concerted uncoupled capture of the nascent benzyl cation by solvent.Replacing a small proportion of the trifluoroethanol in the reaction medium by the more nucleophilic ethanol does not have a drastic effect upon the overall course of the reaction, and a very similar mechanism also appears to be operative in aqueous acetonitrile.
Concurrent Solvolytic and Non-solvolytic Reactions of Benzyl Azoxytoluene-p-sulphonate in Aqueous Trifluoroethanol containing Bases: An Unprecedented Mechanistic Duality
Maskill, H.
, p. 1433 - 1435 (2007/10/02)
Benzyl azoxytoluene-p-sulphonate (1) undergoes heterolytic fragmentation on solvolysis with the anticipated electron flow from benzyl towards the toluene-p-sulphonate leaving group, but suffers concurrent nucleophilic attack by basic solutes at the sulphur atom of the toluene-p-sulphonate moiety with consequent heterolysis and electron flow in the opposite sense, the benzylazoxy group now being the nucleofuge.
A Rate and Product Study of the Effect of Solutes upon the Solvolysis of Benzyl Toluene-p-sulphonate in Aqueous Trifluoroethanol
Maskill, H.
, p. 1241 - 1246 (2007/10/02)
The effects of several electrolytes, including sodium perchlorate, thiocyanate, acetate, and halides, upon the rate and products of solvolysis of benzyl tosylate in 1:1 (v/v) aqueous trifluoroethanol at 25 deg C have been investigated.In the absence of any electrolyte, the ratio of benzyl alcohol to benzyl trifluoroethyl ether is only marginally greater than the molar ratio of water to trifluoroethanol in the reaction medium.Sodium perchlorate gives rise to a kinetic salt effect but not detectable pertubation of the product ratio.Thiocyanate, iodide, and bromide lead to second-order rate terms and the formation of substitution products.Thiocyanate, the most effective nucleophile used, does not affect the internal ratio of the solvent-derived products.We find no evidence of nucleophile capture of carbonium ion intermediates formed in prior rate-determining steps.Chloride, acetate, and hydroxide are very weak nucleophiles in this medium and do not lead to overall rate enhancements.Replacing a small proportion of the trifluoroethanol by ethanol leads to the formation of a low yield of benzyl ethyl ether.There is no evidence of benzl tosylate reacting other than by SN2 mechanism, either uncoupled in reactions with solvent and hard nucleophilic solutes, or coupled with soft nucleophiles such as iodide and thiocyanate.
