Diethylaminosulfurtrifluoride

Fauq, Abdul H.; Singh, Rajendra Prasad; Meshri, Dayal T.

doi:10.1002/047084289x.rd175.pub2

Cited by 8 publications

(6 citation statements)

References 111 publications

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“…2-Acetyl-5-fluoro-2-azabicyclo[2.1.1]hexane-3-carboxylic acid methyl ester ( 7 , Ac-methano-flp-OMe) was synthesized from unlabeled Ac-methano-hyp-OMe ( 6 ) by its reaction with bis(2-methoxyethyl)aminosulfur trifluoride (Deoxo-Fluor), as shown in Scheme . The reaction generally proceeds with the inversion of stereochemistry, but the configuration is retained here because neighboring-group participation of the nitrogen (or possibly the amide oxygen) leads to a double inversion of stereochemistry at the bridge carbon during the fluorination reaction. The stereochemistry of the fluorine on C 1 γ1 (elsewhere, C-5 48,31 ) was confirmed by analyzing the coupling constants between H 1 γ1 (H-5) and H 1 γ21 (H-6 syn ), which is 7.4 Hz.…”

Section: Resultsmentioning

confidence: 99%

Substituted 2-Azabicyclo[2.1.1]hexanes as Constrained Proline Analogues: Implications for Collagen Stability

et al. 2004

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Among the proteinogenic amino acids, only proline is a secondary amine and only proline has a saturated ring. Electronegative substituents on C-4 (that is, C(gamma)) have a substantial effect on the trans/cis ratio of the prolyl peptide bond and the pucker of the pyrrolidine ring. 2-Azabicyclo[2.1.1]hexane is, in essence, a proline analogue with two C(gamma) atoms, one in each of the two prevalent ring puckers of proline. Here, 2-azabicyclo[2.1.1]hexane analogues of 2S-proline, (2S,4S)-4-hydroxyproline, and (2S,4S)-4-fluoroproline residues were synthesized, and their trans/cis ratios were shown to be invariant in a particular solvent. Thus, the substitution of a proline residue on C-4 affects the trans/cis ratio by altering the pucker of its pyrrolidine ring. This finding has implications for the conformation of collagen, which has an abundance of 2S-proline and (2S,4R)-4-hydroxyproline residues, and can be stabilized by (2S,4R)-4-fluoroproline and (2S,4S)-4-fluoroproline residues.

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Section: Resultsmentioning

confidence: 99%

Substituted 2-Azabicyclo[2.1.1]hexanes as Constrained Proline Analogues: Implications for Collagen Stability

et al. 2004

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“…Over time, these liquids are known to discolor, and a redistillation can be required to be used satisfactorily. ( 15 ) Upon use, DAST and Deoxo-Fluor generate free HF which is very volatile (bp 20 °C), highly toxic, extremely corrosive to skin and other tissues including bone, and readily etches glass. ( 16 ) Finally, deoxofluorinations using dialkylaminosulfur trifluorides are problematic in certain cases in that dehydration to an olefin often occurs.…”

Section: Introductionmentioning

confidence: 99%

Aminodifluorosulfinium Salts: Selective Fluorination Reagents with Enhanced Thermal Stability and Ease of Handling^,

et al. 2010

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Diethylaminodifluorosulfinium tetrafluoroborate (XtalFluor-E) and morpholinodifluorosulfinium tetrafluoroborate (XtalFluor-M) are crystalline fluorinating agents that are more easily handled and significantly more stable than Deoxo-Fluor, DAST, and their analogues. These reagents can be prepared in a safer and more cost-efficient manner by avoiding the laborious and hazardous distillation of dialkylaminosulfur trifluorides. Unlike DAST, Deoxo-Fluor, and Fluolead, XtalFluor reagents do not generate highly corrosive free-HF and therefore can be used in standard borosilicate vessels. When used in conjunction with promoters such as Et3N·3HF, Et3N·2HF, or DBU, XtalFluor reagents effectively convert alcohols to alkyl fluorides and carbonyls to gem-difluorides. These reagents are typically more selective than DAST and Deoxo-Fluor and exhibit superior performance by providing significantly less elimination side products.

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“…The liquids also discolor with aging and sometimes require redistillation to be satisfactory. ( 7 ) As a consequence of their explosiveness, DAST-type reagents are subject to strict legal provisions and shipping restrictions. There is therefore a need for deoxofluorinating reagents that do not suffer from the aforementioned deficiencies of dialkylaminosulfur trifluorides.…”

mentioning

confidence: 99%

“…These reagents are fuming liquids that are difficult to handle in humid environments, react violently with water, and do not offer the convenience of handling solids from a manufacturing standpoint. The liquids also discolor with aging and sometimes require redistillation to be satisfactory . As a consequence of their explosiveness, DAST-type reagents are subject to strict legal provisions and shipping restrictions.…”

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confidence: 99%

Aminodifluorosulfinium Tetrafluoroborate Salts as Stable and Crystalline Deoxofluorinating Reagents

et al. 2009

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Aminodifluorosulfinium tetrafluoroborate salts were found to act as efficient deoxofluorinating reagents when promoted by an exogenous fluoride source and, in most cases, exhibited greater selectivity by providing less elimination byproduct as compared to DAST and Deoxo-Fluor. Aminodifluorosulfinium tetrafluoroborates are easy handled crystalline salts that show enhanced thermal stability over dialkylaminosulfur trifluorides, are storage-stable, and unlike DAST and Deoxo-Fluor do not react violently with water.

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Diethylaminosulfurtrifluoride

Cited by 8 publications

References 111 publications

Substituted 2-Azabicyclo[2.1.1]hexanes as Constrained Proline Analogues: Implications for Collagen Stability

Substituted 2-Azabicyclo[2.1.1]hexanes as Constrained Proline Analogues: Implications for Collagen Stability

Aminodifluorosulfinium Salts: Selective Fluorination Reagents with Enhanced Thermal Stability and Ease of Handling^,

Aminodifluorosulfinium Tetrafluoroborate Salts as Stable and Crystalline Deoxofluorinating Reagents

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Diethylaminosulfurtrifluoride

Cited by 8 publications

References 111 publications

Substituted 2-Azabicyclo[2.1.1]hexanes as Constrained Proline Analogues: Implications for Collagen Stability

Substituted 2-Azabicyclo[2.1.1]hexanes as Constrained Proline Analogues: Implications for Collagen Stability

Aminodifluorosulfinium Salts: Selective Fluorination Reagents with Enhanced Thermal Stability and Ease of Handling,

Aminodifluorosulfinium Tetrafluoroborate Salts as Stable and Crystalline Deoxofluorinating Reagents

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Aminodifluorosulfinium Salts: Selective Fluorination Reagents with Enhanced Thermal Stability and Ease of Handling^,