Automated Glycan Assembly of Mycobacterial Hexaarabinofuranoside and Docosasaccharide Arabinan (Araf23) Motifs found on Mycobacterium tuberculosis

Mycobacteria are covered in a thick layer of different polysaccharides that helps to avert the innate immune response. Lipoarabinomannan (LAM) and arabinogalactan (AG) are ubiquitously contained in these envelopes, and rapid access to defined oligo- and polysaccharides is essential to elucidate their structural and biological roles. Arabinofuranose (Araf) residues in LAM and AG are connected either via α-1,2-trans linkages that are synthetically straightforward to install or the more challenging β-(1,2-cis) linkages. Herein, it was demonstrated that automated glycan assembly (AGA) can be used to quickly prepare 1,2-cis-β-Araf as illustrated by the assembly of a highly branched arabinan hexasaccharide and a docosasaccharide arabinan (Araf23) motif

β-Cyclodextrin mediated synthesis of 1,8-dioxooctahydroxanthenes in water

An experimentally simple, efficient Michael addition reaction was developed for the synthesis of various 1,8-dioxooctahydroxanthene derivatives with 1,3-cyclohexanedione/5,5-dimethyl 1,3-cyclohexane dione and different aldehydes by using β-cyclodextrin as a catalyst in water. A biomimetic approach was employed and the corresponding products were obtained in good to excellent yields. β-cyclodextrin can be recovered and reused upto four cycles without loss of catalytic activity

Simple and straight forward synthesis of 2,4-disubstituted quinazolines in aqueous medium

Efficient synthesis of diverse quinazolines from readily available starting materials was achieved in aqueous medium via one-pot protocol. A number of 2,4-disubstituted quinazolines were prepared in moderate to good yields under mild and catalyst-free conditions. Neutral reaction conditions, easy work-up procedures with wide substrate scope and atom economy are the remarkable features of this method

Automated Glycan Assembly of Oligogalactofuranosides Reveals the Influence of Protecting Groups on Oligosaccharide Stability

Galactofurans are an important structural constituent of arabinogalactan and lipopolysaccharides (LPS) ubiquitously present on the envelopes of all Mycobacteria. Key to the automated glycan assembly (AGA) of linear galactofuranosides as long as 20-mers was the identification of thioglycoside building blocks with a fine balance of stereoelectronic and steric effects to ensure the stability of oligogalactofuranoside during the synthesis. A benzoylated galactofuranose thioglycoside building block proved most efficient for oligosaccharide construction

A simple, solvent and catalyst-free green synthetic protocol for α-amino phosphonates

A simple and efficient method for the synthesis of α-amino phosphonates has been developed by using aromatic aldehydes, amines, and trimethyl/triethyl phosphite, under catalyst and solvent free conditions, with the formation of the product in good to excellent yields. This method involves milder reaction conditions, easy work-up, and cleaner reaction profiles, and may have wide spread application in organic synthesis

Yb(OTf)₃‑Catalyzed Desymmetrization of <i>myo</i>-Inositol 1,3,5-Orthoformate and Its Application in the Synthesis of Chiral Inositol Phosphates

A variety of inositol phosphates including <i>myo</i>-inositol 1,4,5-trisphosphate, which is a secondary messenger in transmembrane signaling, were selectively synthesized via Yb­(OTf)₃-catalyzed desymmetrization of <i>myo</i>-inositol 1,3,5-orthoformate using a proline-based chiral anhydride as an acylation precursor. The investigated catalytic system could regioselectively differentiate the enantiotopic hydroxy groups of <i>myo</i>-inositol 1,3,5-orthoformate in the presence of a chiral auxiliary. This key step to generate a suitably protected chiral <i>myo</i>-inositol derivatives is described here as a unified approach to access inositol phosphates

Design of Novel Aminoglycoside Derivatives with Enhanced Suppression of Diseases-Causing Nonsense Mutations

New pseudotrisaccharide derivatives of aminoglycosides that exploit additional interaction on the shallow groove face of the decoding-site rRNA of eukaryotic ribosome were designed, synthesized and biologically evaluated. Novel lead structures (<b>6</b> and <b>7</b> with an additional 7′-OH), exhibiting enhanced specificity to eukaryotic cytoplasmic ribosome, and superior nonsense mutation suppression activity than those of gentamicin, were discovered. The comparative benefit of new leads was demonstrated in four different nonsense DNA-constructs underling the genetic diseases cystic fibrosis, Usher syndrome, and Hurler syndrome