Substitution at the C(7) position of purine nucleotides by a potent electron-withdrawing nitro group facilitates the cleavage of glycosidic bonds under alkaline conditions. This property is useful for sequence-specific cleavage of DNA containing these analogues. Here we describe the preparation of 7-deaza-7-NO(2)-dA and 7-deaza-7-NO(2)-dG using two different approaches, starting from 2'-deoxy-adenosine and 6-chloro-7-deaza-guanine, respectively. These modified nucleosides were converted to nucleotide triphosphates, each of which can replace the corresponding, naturally occurring triphosphate to support PCR amplification. [structure: see text]
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http://dx.doi.org/10.1021/ol051144r | DOI Listing |
Carbohydr Res
January 2025
Glycochemistry Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi, 110067, India. Electronic address:
Glycohybrids are biologically significant molecules with variety of biological functions and are found as structural motifs in numerous natural products. Here, we report the synthesis of various new coumarin-based O-glycoconjugates as glycohybrids that are chirally enriched and bridged by 1,2,3-triazoles ring system. The1,2,3-triazoles bridging was done via CuAAC click-chemistry.
View Article and Find Full Text PDFOrg Biomol Chem
January 2025
Catalysis Laboratory, School of Chemistry, University of Hyderabad, Hyderabad-500 046, India.
Benzothiazole and benzoxazole heterocyclic ring-containing 1,4,5-trisubstituted-1,2,3-triazoles are well known for their wide range of applications in pharmaceutical and medicinal chemistry, but their high-yielding metal-free selective synthesis has always remained challenging as no comprehensive simple protocol has been outlined to date. Owing to their structural and medicinal importance, herein, we synthesized various benzothiazole and benzoxazole heterocyclic ring-containing 1,4,5-trisubstituted-1,2,3-triazoles in high to excellent yields with chemo-/regioselectivity from the library of benzothiazole/benzoxazole-ketones and aryl/alkyl-azides through an enolate-mediated organocatalytic azide-ketone [3 + 2]-cycloaddition under ambient conditions in a few hours. The commercial availability or quick synthesis of the starting materials and catalysts, a diverse substrate scope, chemo-/regioselectivity, quick synthesis of pharmaceutically active known compounds and their analogues, and numerous medicinal applications of functionalized benzothiazole/benzoxazole-triazoles are the key attractions of this metal-free organo-click reaction.
View Article and Find Full Text PDFChemistry
January 2025
Institute of Organic Chemistry PAS: Instytut Chemii Organicznej Polskiej Akademii Nauk, Institute of Organic Chemistry, Kasprzaka 44/52, 01-224, Warsaw, POLAND.
Herein, we report the synthesis and chiroptical characteristics of the first (double) helicenes possesing the 1,4-dihydropyrrolo[3,2-b]pyrrole (DHPP) moiety as their central core. We have developed a three-step synthesis with 6π-electrocyclization accompanied with HBr elimination as its key step. We found that, whereas for smaller periphereal arms double 6π-electrocyclization occurs smoothly forming a double helicene, in the case of longer policyclic aromatic hydrocarbons the reaction becomes less efficient and mono-helicenes are the only products.
View Article and Find Full Text PDFNat Commun
January 2025
Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, PR China.
Allylic ethers and alcohols are essential structural motifs commonly present in natural products and pharmaceuticals. Direct allylic C-H oxygenation of internal alkenes is one of the most direct methods, bypassing the necessity for an allylic leaving group that is needed in the traditional Tsuji-Trost reaction. Herein, we develop an efficient and practical method for synthesizing (E)-allyl ethers from readily available internal alkenes and alcohols or phenols via selective allylic C-H oxidation.
View Article and Find Full Text PDFOrg Lett
January 2025
Division of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
1,1-Difluoroallenes underwent regioselective [2 + 2] and [3 + 2] cycloadditions with aldehydes using Au(I) catalysts. An AuCl catalyst enabled an α,β-selective [2 + 2] cycloaddition of 1,1-difluoroallenes, yielding ()-3-alkylidene-2,2-difluorooxetanes. Conversely, an AuCl(IPr)-AgSbF catalyst facilitated an α,γ-selective [3 + 2] cycloaddition, followed by dehydrofluorination to produce aromatized 2-fluorofurans.
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