Nascent-HBr-Catalyzed Removal of Orthogonal Protecting Groups in Aqueous Surfactants

A short synthesis of carbohydrate derived N-benzyl aminocyclopentitols through N-O bond cleavage of the corresponding isoxazolidine derivatives: Evaluation of their anticancer properties using in vitro and in silico studies

A short synthesis of a potent glycosidase inhibitor N-benzyl-β-D-gluco aminocyclopentitol along with its 2-deoxy, and orthogonally protected 2-O-benzyl, 1,2,3-tri-O-benzyl and 1,2,3-tri-O-acetyl analogues through carbohydrate derived cyclopentane-fused isoxazolidine derivatives has been described herein. The key steps involve NaI mediated vinylation of d-glucose derived 5,6-di-O-mesylated compounds in sealed tube to produce 5,6-dideoxy-l,2-O-isopropylidene-α-D-xylo-hexo-5-enofuranos derivatives in very good yields. Subsequent acetonide deprotection and stereoselective intramolecular nitrone cycloaddition (INC) reaction involving C-4-vinyl functionalities and the latent aldehyde moiety at C-1 yielded various cyclopentano-isoxazolidines. The N-O bond cleavage of the isoxazolidine rings produced the targeted aminocyclopentitols. In vitro anticancer activities of the isoxazolidines and N-benzyl aminocyclopentitols were performed and found only 1,2,3-tri-O-benzyl analogue (20c) of N-benzyl-β-D-gluco aminocyclopentitols emerged as potent anticancer agent with IC50 value 54.90 μM. Furthermore, the molecular docking study confirmed that 20c, compared with the other derivatives, scores higher binding affinity for all the targeted receptors, HSP90, PLK1, and TOP2A.

A mild deprotection of isopropylidene ketals from 2-deoxyglycosides using AcOH/H2O/DME: An efficient regioselective deprotection of terminal isopropylidene ketals

This paper describes a mild and efficient catalytic deprotection method for isopropylidene ketals and benzylidene acetals using AcOH/H2O/DME(1,2-Dimethoxyethane). The method effectively removes ketal and acetal protecting groups from 2-deoxyglycosides which are prone to hydrolysis under acidic conditions. Moreover, it enables the selective removal of the terminal ketal over an internal one.

New Route to Glycosylated Porphyrins via Aromatic Nucleophilic Substitution (SNAr)—Synthesis and Cellular Uptake Studies

Glycoporphyrins are group of compounds of high value for the purpose of photodynamic therapy and other biomedical applications. Despite great progress in the field, new diversity-oriented syntheses of carbohydrate-porphyrin hybrids are increasingly desired. Herein, we present efficient, mild, and metal-free conditions for synthesis of glycoporphyrins. The versatile nature of the SNAr procedure is presented in 16 examples. Preliminary biological studies have been conducted on the cytotoxicity and cellular uptake of the final molecules.

Advancement of the Cleavage Methods of Carbohydrate-derived Isopropylidene and Cyclohexylidene Ketals

Abstract:

Carbohydrates, amino acids, and nucleosides, the fundamental building blocks of complex biomolecules in nature, are essential starting materials for the fabrication of natural and unnatural structural entities, which necessitate the masking and demasking of various functional groups with the utmost chemoselectivity, mildness, and efficiency to avoid unintended bond breaking and formation, as well as associated reactions. Ketals, benzylidene, methoxymethyl, p-methoxybenzyl, silyl ethers, trityl, tert-butyl carbamate, and other functional groups are widely used in modern organic synthesis. In carbohydrate chemistry, the commonly used protecting functionality of isopropylidene and cyclohexylidene ketals necessitates effective methods for selective cleavage. This review summarises different methods for deblocking isopropylidene and cyclohexylidene ketals using inorganic acids, Lewis acid, silica-supported inorganic acids, Amberlite-120 (H+) resin, phosphotungstic acid, Nafion-H, NaBArF4.2H2O, montmorillonite clay, Dowex 50W-X8, camphorsulphonic acid (CSA), ceric ammonium nitrate, molecular iodine, ionic liquids, zeolites and so on.

Metal-free hydroxy and aminocyanation of furanos-3-uloses

TSAO-T and ATSAO-T analogues are molecules of interest that are able to inhibit the reverse transcriptase (RT) of HIV-1 and HCV. We also recently highlighted their antiproliferative properties. In all cases, the spiro cycle was a required group for biological activities, which led chemists to produce many derivatives, especially on this ring. These structures can be accessed through the formation of glycoaminonitriles and glycocyanhydrins using methodologies not always adapted to the synthesis of large quantities. Moreover, these latter are poorly versatile (substrate-dependent), need expensive cyanogenic agents and implies the use of a metal in non-catalytic amounts. For this reason, we report here a new metal-free methodology for the synthesis of glycoaminonitriles and glycocyanhydrins using molecular iodine (I₂).