scholarly journals Branching out at C-2 of septanosides. Synthesis of 2-deoxy-2-C-alkyl/aryl septanosides from a bromo-oxepine

2012 ◽  
Vol 8 ◽  
pp. 522-527 ◽  
Author(s):  
Supriya Dey ◽  
Narayanaswamy Jayaraman
Keyword(s):  
Suzuki Reaction ◽  
Ring Expansion ◽  
Protecting Groups ◽  
Coupling Reactions ◽  
Sonogashira Coupling ◽  
Alkyl Aryl ◽  
Organometallic Reactions ◽  
Bond Forming ◽  
Derivatives Of ◽  
Cyclopropane Derivatives

This paper deals with the synthesis of 2-deoxy-2-C-alkyl/aryl septanosides. A range of such septanoside derivatives was synthesized by using a common bromo-oxepine intermediate, involving C–C bond forming organometallic reactions. Unsaturated, seven-membered septanoside vinyl bromides or bromo-oxepines, obtained through a ring expansion methodology of the cyclopropane derivatives of oxyglycals, displayed a good reactivity towards several acceptor moieties in C–C bond forming Heck, Suzuki and Sonogashira coupling reactions, thus affording 2-deoxy-2-C-alkyl/aryl septanosides. Whereas Heck and Sonogashira coupling reactions afforded 2-deoxy-2-C-alkenyl and -alkynyl derivatives, respectively, the Suzuki reaction afforded 2-deoxy-2-C-aryl septanosides. Deprotection and reduction of the 2-deoxy-2-alkenyl derivative afforded the corresponding 2-deoxy-2-C-alkyl septanoside free of protecting groups. The present study illustrates the reactivity of bromo-oxepine in the synthesis of hitherto unknown septanosides, branching out at C-2, through C–C bond formation with alkyl and aryl substituents.

The Reaction of N-Trimethylsilyl-Substituted Heteroarylamines with Esters and Thioesters: An Efficient Protocol To Access Diheteroarylamides

Synthesis ◽  
2019 ◽  
Vol 51 (08) ◽  
pp. 1779-1790
Author(s):  
Ana Koperniku ◽  
Maryam Zamiri ◽  
David Grierson
Keyword(s):  
Parallel Synthesis ◽  
Amide Bond ◽  
Coupling Reactions ◽  
Trimethylsilyl Derivative ◽  
Vacuum Filtration ◽  
Bond Forming ◽  
Compound Libraries ◽  
Amide Coupling ◽  
Derivatives Of

The S-benzyl thioester and methyl ester derivatives of a representative 4-pyridinone-based carboxylic acid were sufficiently activated to react efficiently in amide coupling reactions with the amide anion generated in situ from the N-trimethylsilyl derivative of different weakly nucleophilic heteroarylamines. In acetonitrile as solvent, the precipitated diheteroarylamide products were isolated in pure form by vacuum filtration. This simple amide bond forming protocol can be readily adapted to the parallel synthesis of compound libraries.

Sugar-modified derivatives of cytostatic 6-(het)aryl-7-deazapurine nucleosides: 2′-C-methylribonucleosides, arabinonucleosides and 2′-deoxy-2′-fluoroarabinonucleosides

2011 ◽  
Vol 76 (8) ◽  
pp. 957-988 ◽  
Author(s):  
Petr Nauš ◽  
Pavla Perlíková ◽  
Radek Pohl ◽  
Michal Hocek
Keyword(s):  
Antiviral Activity ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Alkyl Aryl ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
Derivatives Of

A series of novel sugar-modified derivatives of cytostatic 6-hetaryl-7-deazapurine ribonucleosides: 2′-C-methylribonucleosides, arabinonucleosides and 2′-deoxy-2′-fluoroarabinonucleosides bearing an alkyl, aryl and hetaryl group in position 6 were prepared by palladium catalyzed cross-coupling reactions of corresponding (protected) 6-chloro-(7-fluoro)-7-deazapurine nucleosides with (het)arylboronic, hetarylstannanes and trimethylaluminium eventually followed by deprotection. Key intermediate 6-chloro-7-deazapurine 2′-C-methyl-β-D-ribofuranoside was prepared via a stereoselective nucleobase anion glycosylation with toluoyl-protected 1,2-anhydro-2-C-methylribofuranose. The 1,2-anhydro sugar was synthesized in 3 steps starting from readily available 2-C-methylribonolactone. The 6-chloro-7-deazapurine arabinofuranoside intermediate was obtained by epimerization from 3′,5′-protected 6-chloro-7-deazapurine ribofuranoside via 2′-hydroxyl oxidation followed by reduction. None of the prepared compounds showed any considerable cytostatic or antiviral activity.

New 2-Alkynyl Derivatives of the Acyclic Nucleoside 9-(2,3-Dihydroxypropyl)adenine and Their 6-Guanidinopurine Counterparts as Potential Effectors of Adenosine Receptors

2003 ◽  
Vol 68 (11) ◽  
pp. 2201-2218 ◽  
Author(s):  
Michal Česnek ◽  
Antonín Holý ◽  
Milena Masojídková
Keyword(s):  
Adenosine Receptors ◽  
Sonogashira Coupling ◽  
Acyclic Nucleoside ◽  
Derivatives Of

A series of the new 2-alkynyl derivatives of the acyclic nucleoside 9-(2,3-dihydroxypropyl)- adenine and their 6-guanidinopurine analogues were prepared by the Sonogashira coupling. The effect of the prepared compounds on A1 and A2A receptors was examined.

scholarly journals A One-Pot Approach to Novel Pyridazine C-Nucleosides

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2341
Author(s):  
Flavio Cermola ◽  
Serena Vella ◽  
Marina DellaGreca ◽  
Angela Tuzi ◽  
Maria Rosaria Iesce
Keyword(s):  
Organic Chemistry ◽  
Research Field ◽  
Modified Nucleosides ◽  
Protecting Groups ◽  
Coupling Reactions ◽  
One Pot ◽  
Pharmacological Interest ◽  
Classical Methodology ◽  
Glycosyl Donor ◽  
Neutral Conditions

The synthesis of glycosides and modified nucleosides represents a wide research field in organic chemistry. The classical methodology is based on coupling reactions between a glycosyl donor and an acceptor. An alternative strategy for new C-nucleosides is used in this approach, which consists of modifying a pre-existent furyl aglycone. This approach is applied to obtain novel pyridazine C-nucleosides starting with 2- and 3-(ribofuranosyl)furans. It is based on singlet oxygen [4+2] cycloaddition followed by reduction and hydrazine cyclization under neutral conditions. The mild three-step one-pot procedure leads stereoselectively to novel pyridazine C-nucleosides of pharmacological interest. The use of acetyls as protecting groups provides an elegant direct route to a deprotected new pyridazine C-nucleoside.

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

Synthesis ◽  
2020 ◽  
Vol 52 (17) ◽  
pp. 2483-2496
Author(s):  
Johannes F. Teichert ◽  
Lea T. Brechmann
Keyword(s):  
Coupling Reaction ◽  
Reactive Intermediates ◽  
Transfer Hydrogenation ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Starting Point ◽  
Bond Forming Reactions ◽  
Hydrogenation Reactions ◽  
Multicomponent Coupling Reactions ◽  
Trapping Reactions

The key reactive intermediate of copper(I)-catalyzed alkyne semihydrogenations is a vinylcopper(I) complex. This intermediate can be exploited as a starting point for a variety of trapping reactions. In this manner, an alkyne semihydrogenation can be turned into a dihydrogen­-mediated coupling reaction. Therefore, the development of copper-catalyzed (transfer) hydrogenation reactions is closely intertwined with the corresponding reductive trapping reactions. This short review highlights and conceptualizes the results in this area so far, with H2-mediated carbon–carbon and carbon–heteroatom bond-forming reactions emerging under both a transfer hydrogenation setting as well as with the direct use of H2. In all cases, highly selective catalysts are required that give rise to atom-economic multicomponent coupling reactions with rapidly rising molecular complexity. The coupling reactions are put into perspective by presenting the corresponding (transfer) hydrogenation processes first.1 Introduction: H2-Mediated C–C Bond-Forming Reactions2 Accessing Copper(I) Hydride Complexes as Key Reagents for Coupling Reactions; Requirements for Successful Trapping Reactions 3 Homogeneous Copper-Catalyzed Transfer Hydrogenations4 Trapping of Reactive Intermediates of Alkyne Transfer Semi­hydrogenation Reactions: First Steps Towards Hydrogenative Alkyne Functionalizations 5 Copper(I)-Catalyzed Alkyne Semihydrogenations6 Copper(I)-Catalyzed H2-Mediated Alkyne Functionalizations; Trapping of Reactive Intermediates from Catalytic Hydrogenations6.1 A Detour: Copper(I)-Catalyzed Allylic Reductions, Catalytic Generation of Hydride Nucleophiles from H2 6.2 Trapping with Allylic Electrophiles: A Copper(I)-Catalyzed Hydro­allylation Reaction of Alkynes 6.3 Trapping with Aryl Iodides7 Conclusion

Lewis Acid-Promoted Suzuki Reaction using Palladium Chloride Anchored on a Polymer as a Catalyst

2008 ◽  
Vol 61 (8) ◽  
pp. 610 ◽  
Author(s):  
Guozhi Fan ◽  
Hanjun Zhang ◽  
Siqing Cheng ◽  
Zhandong Ren ◽  
Zhijun Hu ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Lewis Acid ◽  
Lewis Acids ◽  
Heterogeneous Catalysts ◽  
Suzuki Reaction ◽  
Cross Coupling ◽  
Palladium Chloride ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Recoverable Catalyst

Palladium chloride anchored on polystyrene modified by 5-amino-1,10-phenanthroline was prepared and used as an efficient recoverable catalyst for Suzuki cross-coupling reactions. The heterogeneous catalysts can be easily separated from the reaction mixture and reused for five cycles without significant Pd leaching and loss of catalytic activity. Rate enhancement in the Suzuki reaction by Lewis acids was also studied.

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