Triflic Anhydride-Mediated Unprecedented Reactivities of Diacetonide Endoglucofuranose and Ribose Tetracetate: Direct Access to γ-Butenolides and Oxazoles.

Herein, we present two unprecedented reactions for the synthesis of γ-butenolides and oxazoles, leveraging Tf2O's promoted reactivity of nitriles with diacetonide endoglucofuranose and 1,2,3,5-tetra-O-acetyl-ß-d-ribofuranose. This method is highly efficient and straightforward and employs a one-step, metal-free protocol. It is effective with both aromatic and aliphatic nitriles and demonstrates a broad substrate scope. Our approach provides a versatile and practical pathway for the synthesis of structurally diverse compounds, significantly expanding the utility of Tf2O in synthetic chemistry.

Triflic Anhydride-Mediated Approach to Furo[3,2-b]furans from Diacetonide Protected Furanoses.

Trifluoromethanesulfonic anhydride (Tf2O) exhibits excellent reactivity as an electrophile, serving as a highly versatile reagent in diverse chemical transformations. Herein, we report an operationally simple, efficient, unique, and practical one-step strategy for synthesizing diverse valuable structures bearing furo[3,2-b]furans core leveraging Tf2O's promoted reactivity of nitriles with diacetonide protected furanose. Furthermore, we demonstrate the potential of furo[3,2-b]furan as a precursor for complex structures through 1,3-dipolar cycloaddition.

A path from synthesis to emergency use authorization of molnupiravir as a COVID-19 therapy.

Coronaviruses are a group of enveloped viruses with non-segmented, single-stranded, and positive-sense RNA genomes. It belongs to the 'Coronaviridae family', responsible for various diseases, including the common cold, SARS, and MERS. The COVID-19 pandemic, which began in March 2020, has affected 209 countries, infected over a million people, and claimed over 50,000 lives. Significant efforts have been made by repurposing several approved drugs including antiviral, to combat the COVID-19 pandemic. Molnupiravir is found to be the first orally acting efficacious drug to treat COVID-19 cases. It was approved for medical use in the UK in November 2021 and other countries, including USFDA, which granted approval an emergency use authorization (EUA) for treating adults with mild to moderate COVID-19 patients. Considering the importance of molnupiravir, the present review deals with its various synthetic strategies, pharmacokinetics, bio-efficacy, toxicity, and safety profiles. The comprehensive information along with critical analysis will be very handy for a wide range of audience including medicinal chemists in the arena of antiviral drug discovery especially anti-viral drugs against any variant of COVID-19.

Base-Mediated Transformation of Glycals to Their Corresponding Vinyl Iodides and Their Application in the Synthesis of C-3 Enofuranose and Bicyclic 3,4-Pyran-Fused Furanose.

A simple method for the iodination of unsaturated sugars to form sugar vinyl iodides was developed under oxidant-free conditions using NaH/DMF/iodine as a reagent system at ambient temperature. 2-Iodoglycals bearing ester, ether, silicon, and acetonide protection were synthesized in good to excellent yield. 3-Vinyl iodides derived from 1,2:5,6-diacetonide glucofuranose were transformed to C-3 enofuranose and bicyclic 3,4-pyran-fused furanose via Pd-catalyzed C-3 carbonylation and intramolecular Heck reaction, respectively, as the key step.

Correction: Diastereoselective synthesis of glycopyrans 1,2-annulated with dioxazinanes from 1,2-anhydrosugars and N-substituted nitrones.

Correction for 'Diastereoselective synthesis of glycopyrans 1,2-annulated with dioxazinanes from 1,2-anhydrosugars and N-substituted nitrones' by Ajaz Ahmed et al., Org. Biomol. Chem., 2022, 20, 1436-1443, DOI: 10.1039/d1ob02310a.

Diastereoselective synthesis of glycopyrans 1,2-annulated with dioxazinanes from 1,2-anhydrosugars and N-substituted nitrones.

1,2-Annulated pyranose sugars fused with six membered rings have emerged as an important class of carbohydrates with wide biological and synthetic utility. We now describe zinc chloride catalyzed one pot diastereoselective synthesis of sugar fused dioxazinanes from 1,2-anhydro sugars and N-substituted aromatic nitrones. Various aromatic nitrones with different substituents undergo the reaction smoothly. The developed strategy works well with both ester and ether protection on the sugar and proceeds under mild reaction conditions. The mechanism seems to involve activation of the anhydrosugar by ZnCl2 for nucleophilic attack by the nitrone followed by cyclization.

Switchable reactivity of 2-benzoyl glycals towards stereoselective access of 1-3 and 1-1 S/O linked disaccharides.

We have developed a synthesis of 1-3 and 1-1 disaccharides from 2-benzoyl glycal and anomeric thiol and/or hydroxy sugar acceptors under mild conditions at room temperature. The regio and stereo-selectivity of the newly formed inter-glycosidic linkages are dependent on the nature of the glycal donor (D or L) and anomeric acceptor.