Diethylaminosulfur Trifluoride Research Articles

ChemInform Abstract: Allylic Fluorides via the Cleavage of Tertiary Cyclopropyl Silyl Ethers with Diethylaminosulfur Trifluoride.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Steroidal allylic fluorination using diethylaminosulfur trifluoride: A convenient method for the synthesis of 3β-acetoxy-7α-and 7β-fluoroandrost-5-en-17-one

This paper discusses our findings regarding fluorination of the diastereomeric 3β-acetoxy-7-hydroxyandrost-5-en-17-ones ( 3 and 4 ) at the allylic 7-hydroxyl group using diethylaminosulfur trifluoride under various experimental conditions. The reaction led to the formation of allylic 7α- and 7β-fluoro derivatives, 6 and t7 , contaminated with small amounts of 3β-acetoxy-5α-fluoroandrost-6-en-17-one ( 8 ), the rearrangement product, and 3β-acetoxyandrosta-4,6-dien-17-one ( 9 ), the elimination product. However, synthesis of 3β-acetoxy-7α-fluoroandrost-5-en-17-one ( 6 ) and 3β-acetoxy-7β-fluoroandrost-5-en-17-one ( t7 ) has been achieved in high isomeric purity by careful manipulation of the experimental conditions. Also included herein is a convenient chemical synthesis of pure 3β-acetoxy-7α-hydroxyandrost-5-en-17-one ( 4 ) and 3β-acetoxy-7β-hydroxyandrost-5-en-17-one ( 3 ), the starting materials for the present fluorination reaction. The structure of a degradation product, 3β-acetoxy-5α-hydroxyandrost-6-en-17-one ( 5 ), has been established by X-ray diffraction analysis to ascertain unambiguously its absolute configuration.

ChemInform Abstract: Fluorination of 2‐Oxoethane Derivatives with Diethylaminosulfur Trifluoride (DAST).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Reactions of (Diethylamino)sulfur Trifluoride (DAST) with Methyl 5‐O‐ Benzyl‐β‐D‐arabino‐ and ‐xylo‐furanosides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

α-Fluoro analogues of inflammation inhibiting α-arylpropionic acids

2-Aryl-2-fluoropropionic acids were prepared by treatment of either ethyl α-hydroxy-carboxylates or cyanohydrin O-silyl ethers with diethylaminosulfur trifluoride and subsequent hydrolysis. The methyl ester of 2-fluoro-2-(4-isobutylphenyl)propionic acid (“α-fluoroibuprofen”) was submitted to an enzymatic racemate resolution.

Synthesis of α-fluorinated-α,α-difunctionalized sulfides and sulfones

The highly functionalized organofluorine compounds 3a-c were prepared from the activated dichlorinated sulfides 2a-c by displacement of a chlorine atom using nucleophilic fluorination agents such as dihydrogenfluoride polymer-supported. Fluorination of sulfoxides 5a-c with diethylaminosulfur trifluoride gives monofluoro sulfides 6a-c, subsequently transformed into α-chloro-α-fluoro sulfides 3a-c and sulfones 7a-c.

Reactions of (Diethylamino)Sulfur Trifluoride (DAST) with Methyl-5-O-Benzyl-β-D-arabino- and -xylo-furanosides

Reaction of (diethylamino)sulfur trifluoride (DAST) with methyl-5-O-benzyl-β-D-arabinofuranoside (1) in CH2Cl2 at room temperature for 3-5 h, followed by silica gel column chromatography afforded ribo2 and lyxo3 fluorides in 41 and 21% yield, respectively. Under similar conditions with xylo-isomer 4 as starting material, epoxide 5 and ribo fluoride 6 were isolated in 33 and 36% yield, respectively.

Fluorination of 2-oxo-ethane derivatives with diethylaminosulfur trifluoride (DAST)

The fluorination of 2-oxo-ethane derivatives with DAST is described. The use of ZnI 2 as a catalyst improves the yield in the fluorination of 2-phenyl-2-oxo-acetonitrile with DAST.

Anomalous fluorinations of 3-aryl-2-hydroxypropanoic esters by diethylaminosulfur trifluoride (DAST)

Treatment of 3-aryl-2-hydroxypropanoic esters 8 with diethylaminosulfur trifluoride (DAST) gives considerable amounts of rearranged 2-aryl-3-fluoropropanoic esters 12 together with the expected products 11. The extent of rearrangement is dependent on solvent and on the substitution pattern of the aryl ring; the mechanism of rearrangement probably involves anchimeric assistance by the aryl group in the SN1 component of the reaction pathway. Recation of the isomeric 3-hydroxy-2-phenylpropanoic ester 13 shows much less rearrangement under similar conditions, and an elimination product 21 is also obtained.

Allylic fluorides via the cleavage of tertiary cyclopropyl silyl ethers with diethlaminosulfur trifluoride

Treatment of tertiary cyclopropyl silyl ethers with diethylaminosulfur trifluoride (DAST) causes ring opening to give allylic fluorides in moderate to high yields.

Synthesis and antiviral activity of 6-chloropurine arabinoside and its 2'-deoxy-2'-fluoro derivative.

6-Chloropurine arabinoside (3a) was obtained by treatment of the 2'-O-acetylated congener (2) with ammonia in methanol. The 3',5'-di-O-tritylated riboside (6) was allowed to react with diethylaminosulfur trifluoride (DAST) in the presence of pyridine to give the 2'-deoxy-2'-fluoroarabinoside (7), from which 6-chloro-9-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)purine (3b) was obtained. The antiviral effects of 3a and 3b were assayed against several DNA and RNA viruses. Only 3a displayed potent activity against varicella-zoster virus (VZV). This antiviral activity was dependent on phosphorylation by the VZV-induced thymidine kinase (TK). Compound 3a showed moderate activity against other DNA viruses, herpes simplex type 1 (HSV-1) and type 2 (HSV-2), and vaccinia virus. They were equally active against TK- and TK+ strains of HSV-1, which suggests that the HSV-1-encoded TK does not play a role in the anti-HSV-1 activity. No activity was noted with any of the compounds against various RNA viruses, including human immunodeficiency virus, at subtoxic concentrations.

ChemInform Abstract: Reaction of Secondary Amides with Diethylaminosulfur Trifluoride.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: (Diethylamino)sulfur Trifluoride (DAST) as a Useful Reagent for the Preparation of 2‐Oxazolines from 1,2‐Amido Alcohols.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A Chemical and Solid-State 19F MAS NMR Investigation of Oxygen Functionality in Lignite: The Fluorination of Low-Rank Coal with Diethylaminosulfur Trifluoride

The oxygen functionality in low-rank coals can be converted into their fluoride equivalents by treatment of the coal with diethylaminosulfur trifluoride (DAST). The generated fluoride functional groups are identified by solid-state 19 F MAS NMR spectroscopy. The presence and nature of oxygen functionality is inferred from these species. Resolution in the 19 F chemical shift dimension of solid-state 19 F NMR spectra of DAST-treated coals is sufficient to allow the differentiation of primary and secondary fluorides and to distinguish aromatic and aliphatic carboxylic acid fluorides. By virtue of high 19 F nuclear sensitivity and isotopic abundance, 19 F MAS NMR permits the detection of functional groups at part per thousand level. This work reports the first clear evidence for the presence of low concentrations of primary and secondary alcohols in lignite, and for the separate identification of aliphatic and aromatic carboxylic acid functions in this coal.

Synthesis and antimalarial activities of several fluorinated artemisinin derivatives.

The carbonyl groups in several artemisinin derivatives were converted into geminal difluorinated compounds on treatment with diethylaminosulfur trifluoride. A number of other mono- and polyfluorinated artemisinin derivatives were prepared. Their in vitro antimalarial activities were all equal to or greater than the nonfluorinated analogs or precursors.

A general method for the preparation of 1,1-bis(trifluoromethyl)substituted olefins

The title compounds are prepared by treatment of 1,1-difluoro-2-trifluoromethyl-1-alken-3-ols ( 1) with diethylaminosulfur trifluoride (DAST) with high regioselectivity. The alcohols ( 1) are obtained by the reaction of 2-pentafluoropropenyllithium with aldehydes and ketones.

Reaction of secondary amides with diethylaminosulphur trifluoride

A variety of fluoroimines are produced from the reaction of secondary amides with diethylaminosulphur trifluoride.

Syntheses of 4′-deoxy-α-maltosyl fluoride and 4″-deoxy-α-maltotriosyl fluoride as probes of α-glucanotransferase mechanisms

4′-Deoxy-α-maltosyl fluoride and 4″-deoxy-α-maltotriosyl fluoride were synthesized to serve as mechanistic probes for α-glucanotransferases such as the glycogen debranching enzyme. The deoxy derivatives were prepared starting from maltose and maltotriose, respectively. Deoxygenation of the terminal 4-hydroxyl group was accomplished by radical reduction of the iodo sugar formed after iodide displacement of the corresponding protected triflate. The anomeric fluoride was introduced by treatment of the protected hemiacetal with diethylaminosulfur trifluoride, predominantly giving the β-anomeric product. Conversion to the α anomer was achieved using HF · pyridine.

Reaction of paclitaxel and 10-desacetyl baccatin III with diethylamino sulfurtrifluoride

Reaction of protected paclitaxel with diethylamino sulfurtrifluoride (DAST), to furnish the 7-fluoro paclitaxel, gives a mixture of four products, two of which have not been previously reported. The product distribution is shown to be solvent dependent. An efficient process for the preparation of the parent 7-α-fluoro baccatin III from 10-desacetyl baccatin III is also described.

Reaction of diethylaminosulfur trifluoride with diols

Diethylaminosulfur trifluoride (DAST) reacts with dialcohols to give difluorides, sulfite esters or cyclic ethers depending on the number of carbons separating the two alcohol groups. Vicinal and 1,3-diols give large amounts of sulfite ester products while butane-1,4-diol gives almost exclusively the cyclic ether tetrahydrofuran. Terminal dialcohols longer than four carbons give primarily difluoride products. Semiempirical calculations indicate a preference for cyclic intermediates when four or less carbons separate the two alcohol moieties. These cyclic intermediates lead directly to the cyclic ethers and sulfite ester products.