Radical Deoxygenation Research Articles

Radical deoxygenation and dehalogenation of nucleoside derivatives with hypophosphorous acid and dialkyl phosphites

Hypophosphorous acid and dialkyl phosphites are effective radical reducing agents for O-thiocarbonyl groups or halides at the sugar part of nucleoside derivatives and give the corresponding hydrocarbons in high yield.

ChemInform Abstract: Radical Deoxygenation of Alcohols via Their Trifluoroacetate Derivatives with Diphenylsilane.

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.

Improved synthesis of 9-(2,3-dideoxy-2-fluoro-β-d-threo-pentofuranosyl)adenine (FddA) using triethylamine trihydrofluoride

An improved synthesis of 9-(2,3-dideoxy-2-fluoro-β-d-threo-pentofuranosyl)adenine (1, FddA) via a fluorination of 3′-O-benzoyl-5′-O-tritylriboside (4a) using noncorrosive triethylamine trihydrofluoride (Et3N·3HF) is described. The method is suitable for large-scale synthesis. In particular, the synthesis of the pivotal intermediate 4a was much improved in avoidance of the use of toxic tin reagent. Radical deoxygenation with several silanes was also studied. The total yield of FddA from 6-chloropurine riboside (2) in this study was greater than that we reported previously.

Radical deoxygenation of alcohols via their trifluoroacetate derivatives with diphenylsilane

Trifluoroacetate derivatives of alcohols can be used as precursors for the radical deoxygenation of alcohols with diphenylsilane. The reaction afforded high isolated yields of the deoxygenated products and neutral reaction conditions.

Introduction of a benzoyl group onto 6-chloropurine riboside in aqueous solution and its application to the synthesis of nucleoside derivatives.

A benzoyl group was introduced onto the 3'-hydroxyl group of 6-chloropurine riboside by treatment with benzoic anhydride in the presence of a base in aqueous solution. The product (3b) was converted to 9-(2,3-Di-deoxy-2-fluoro-beta-D-threo-pentofuranosyl)adenine (1, FddA) in 6 steps, including radical deoxygenation.

Efficient large-scale radical deoxygenation in alcoholic solvents using sodium hypophosphite and a phase-transfer agent: application to erythromycins.

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTEfficient Large-Scale Radical Deoxygenation in Alcoholic Solvents Using Sodium Hypophosphite and a Phase-Transfer Agent: Application to ErythromycinsAlexandra E. Graham, Albert V. Thomas, and Rachel YangView Author Information Process Development, Chemical and Agricultural Products Division, Abbott Laboratories, 1401 Sheridan Road, North Chicago, Illinois 60064-4000 Cite this: J. Org. Chem. 2000, 65, 8, 2583–2585Publication Date (Web):March 28, 2000Publication History Received20 October 1999Published online28 March 2000Published inissue 1 April 2000https://doi.org/10.1021/jo991645oCopyright © 2000 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views595Altmetric-Citations25LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (72 KB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information SUBJECTS:Alcohols,Anions,Redox reactions,Salts,Solvents Get e-Alerts

The “β-Fluorine Effect” in the Non-Metal Hydride Radical Deoxygenation of Fluorine-Containing Nucleoside Xanthates

An alternative method to conduct a Barton-McCombie deoxygenation in nucleosides is described. The utility of the procedure is limited to structures with an electronegative substituent, particularly fluorine, in the β-position relative to the radical center. The process is radical in nature and triggered by peroxides. The abstraction of hydrogen from the solvent is favorably influenced by the presence of a β-fluorine.

Synthesis of 9-(2-Deoxy-2-fluoro-.BETA.-D-arabinofuranosyl)adenine Bearing a Selectively Removable Protecting Group.

A facile and practicam method to infroduce fluorine at the up-side of the 2'-carbon of nucleosides is described. 6-Chloropurine riboside 3 was converted to the 3'-O-benzoate 4a via a stannylene complex, then converted to the 3'-O-benzoyl-5'-O-tritylriboside 5a. In the presence of pyridine, migration of the 3'-benzoyl groups of 4a and 5a to 2'-OH was rather slow. Hence, 5a was reacted with diethylaminosulfur trifluoride (DAST) in CH2Cl2 in the presence of pyridine to give the 2'-deoxy-2'-fluoroarabinoside 6 in good yield. The 3'-O-benzoyl-5'-O-trityl protecting system was easy to deprotect selectively. Thus, treatment of 6 with ammonia in MeOH gave the 5'-O-trityl compound 7, which was subjected to esterificaiton with phenyl chlorothionoformate, radical deoxygenation with tris(trimethylsilyl)silane and acid treatment to afford 9-(2, 3-dideoxy-2-fluoro-β-D-threo-pento-furanosyl)adenine(FddA) 2. In addition, acid treatment of 7 gave 9-(2-deoxy-2-fluoro-β-D-arabinofuranosyl)adenine (FdaraA) 1.

1,2-Di- O-acetyl-5- O-benzoyl-3-deoxy- l- erythro-pentofuranose, a convenient precursor for the stereospecific synthesis of nucleoside analogues with the unnatural β- l-configuration

The title compound 1,2-di- O-acetyl-5- O-benzoyl-3-deoxy- l- erythro-pentofuranose ( 5), a useful precursor for the stereospecific synthesis of β- l-nucleoside analogues as potential antiviral agents, has been synthesised by a multi-step reaction sequence from l-xylose with a 38% overall yield. The preparation involved conversion of l-xylose to 1,2- O-isopropylidene-α- l-xylofuranose which, upon selective 5-O-benzoylation and subsequent radical deoxygenation, provided the protected 3-deoxy sugar derivative. Finally, cleavage of the acetonide group gave the resulting 5- O-benzoyl-3-deoxy- l- erythro-pentose which was acetylated to afford crystalline α,β- 5.

Stereospecific synthesis of unnatural β-L-enantiomers of 2-chloroadenine pentofuranonucleoside derivatives

2′,3′-Dideoxy- (1), 2′,3′-unsaturated- (2), 2′,3′-dideoxy-3′-fluoro- (3), 3′-azido-2′,3′-dideoxy- (4) and 2′-deoxy- (5) β-L-ribofuranonucleosides of 2-chloroadenine have been synthesised and their antiviral properties examined. All these derivatives were stereospecifically prepared by glycosylation of 2,6-dichloropurine with a suitable peracylated L-xylo-furanose (6). Treatment of the resulting protected β-L-nucleoside with methanolic ammonia followed by appropriate chemical modifications gave the 2-chloro-9-(2-deoxy-β-L-threo-pentofuranosyl)adenine 11. Its 5′-O-benzoyl derivative 12 was then converted to nucleosides 1 and 2 via radical deoxygenation reaction or base-promoted β-elimination of the corresponding mesyl ester. Additionally, compounds 3–5 were obtained from 12 either by reaction with (diethylamino)sulfur trifluoride or via Mitsunobu reactions using diphenylphosphoryl azide or benzoic acid as incoming nucleophiles. The prepared compounds were tested for their activity against HIV and HBV viruses, but they did not show significant antiviral activity nor cytotoxicity.

ChemInform Abstract: Diphenylphosphine Oxide: An Alternative to Organotin Hydrides in the Radical Deoxygenation of 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.

Diphenylphosphine Oxide: An Alternative to Organotin Hydrides in the Radical Deoxygenation of Alcohols

Various S-methyl dithiocarbonates of tertiary and secondary alcohols are effectively deoxygenated in high isolated yields by treatment with diphenylphosphine oxide and various radical initiators in boiling dioxane. Deoxygenation of S-methyl dithiocarbonate of primary alcohols can be accomplished similarly in boiling xylenes.

ChemInform Abstract: Phosphine‐Boranes as Selective Reagents for the Radical Deoxygenation of a Hindered Secondary Alcohol.

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: Radical Deoxygenation of Alcohols via Their S‐Methyl Dithiocarbonate Derivatives with Di‐n‐butylphosphine Oxide as Hydrogen Atom Donor.

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.

Phosphine-boranes as selective reagents for the radical deoxygenation of a hindered secondary alcohol

The xanthate of a hindered secondary alcohol can be deoxygenated easily with phosphine-boranes and AIBN in a high yielding radical chain reaction. A similar efficient olefin forming reaction has been seen with a 1,2-dixanthate under the same conditions. In contrast to tin hydride based reagents phosphine-boranes do not reduce chlorides or bromides.

ChemInform Abstract: Tributyltin Hydride‐Induced Free Radical Deoxygenation of the Cyclic Thionocarbonates of threo‐2,3‐Dihydroxy Esters and Ketones.

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.

Radical Deoxygenation of AlcoholsviaTheirS-Methyl Dithiocarbonate Derivatives with Di-n-butylphosphine Oxide as Hydrogen Atom Donor

Radical Deoxygenation of Alcohols<i>via</i>Their<i>S</i>-Methyl Dithiocarbonate Derivatives with Di-<i>n</i>-butylphosphine Oxide as Hydrogen Atom Donor

Tributyltin Hydride-Induced Free Radical Deoxygenation of the Cyclic Thionocarbonates of Threo-2,3-Dihydroxy Esters and Ketones

: A practical and enantiospecific method for the synthesis of optically pure β-hydroxy esters and ketones is described. The key reaction is free radical deoxygenation of the cyclic thionocarbonates of threo-2,3-dihydroxy esters and ketones with tributyltin hydride.

Synthesis of 6-Hydroxy-L-Daunosamine and L-Daunosamine Derivatives

ABSTRACT Methyl 3-trifluoroacetamido-2,3-dideoxy-α-L-lyxo-hexopyranoside (19) has been synthesized from D-glucose derivatives following two pathways. The first one involving 1,2:5,6-di-O-isopropylidene-α-D-glucopyranose as starting material is mainly based upon azidation at C-3, inversion of configuration at C-5 and then radical deoxygenation at C-2 (13 steps and 10% overall yield). This pathway also afforded methyl N-trifluoroacetyl-α-L-daunosamine 22. The second pathway, which started from tri-O-acetyl-D-glucal, relied essentially upon Michael addition of N3H on the corresponding hex-2-enose and glycosidation of the two pivaloyl compounds 33 and 34. After the β-D-ribo isomer 34 was subsequently converted into its β-methyl glycoside 28b, inversion of configuration at C-5 was carried out via the formation of the 6-bromo-sugar 36, followed by formation of the hex-5-enopyranoside 37. Hydroboration of 37 stereoselectively afforded 38, followed by catalytic hydrogenation and trifluoroacetylation to give 19.

Total synthesis of (±)-α-lycorane and 4,5-dehydroanhydrolycorine

The total syntheses of (±)-α-lycorane and dehydroanhydrolycorine are described. The key intermediate in both approaches is the hydroindolone 5, prepared from the [1+4] cycloaddition reaction of 1-isocyanatocyclohexene and cyclohexyl isocyanide. Alkylation of 5 with arylbromide 6 afforded 7. Hydrolysis of enamide 7 followed by reduction of the resultant enol yielded 10 as a single diastereomer. Radical-based cyclization of this intermediate gave 11 possessing the requisite trans-fusion between rings B and C in good yield. Radical deoxygenation followed by reduction of the amide carbonyl function afforded (±)-α-lycorane. Similarly, alkylation of 5 with 6-(chloromethyl)-5-iodo-1,3-benzodioxole gave 14. Treatment of 14 with Pd(OAc) 2 employing the Jeffery modification of the Heck reaction gave tetracycle 9. Hydrolysis of 9 followed by oxidation with DDQ afforded 15. Reduction of the two carbonyl functions in this material using lithium aluminum hydride afforded 4-hydroxyanhydrolycorine ( 16). Mesylation of the hydroxyl group led to rapid, spontaneous elimination producing anhydrodehydrolycorine.