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1. Enantiomeric Separation of New Chiral Azole Compounds

   https://doi.org/10.3390/molecules26010213  

   Kenari, Marziyeh E.; Putman, Joshua I.; Singh, Ravi P.; Fulton, Brandon B.; Phan, Huy; Haimour, Reem K.; Tse, Key; Berthod, Alain; Lovely, Carl J.; Armstrong, Daniel W. (January 2021, Molecules)

   null (Ed.)

   Twelve new azole compounds were synthesized through an ene reaction involving methylidene heterocycles and phenylmaleimide, producing four oxazoles, five thiazoles, and one pyridine derivative, and ethyl glyoxylate for an oxazole and a thiazole compound. The twelve azoles have a stereogenic center in their structure. Hence, a method to separate the enantiomeric pairs, must be provided if any further study of chemical and pharmacological importance of these compounds is to be accomplished. Six chiral stationary phases were assayed: four were based on macrocyclic glycopeptide selectors and two on linear carbohydrates, i.e., derivatized maltodextrin and amylose. The enantiomers of the entire set of new chiral azole compounds were separated using three different mobile phase elution modes: normal phase, polar organic, and reversed phase. The most effective chiral stationary phase was the MaltoShell column, which was able to separate ten of the twelve compounds in one elution mode or another. Structural similarities in the newly synthesized oxazoles provided some insights into possible chiral recognition mechanisms. 

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2. Optically active distorted cyclic triptycenes: chiral stationary phases for HPLC

   https://doi.org/10.1039/C8RA04434A  

   Ikai, Tomoyuki; Nagata, Naoya; Awata, Seiya; Wada, Yuya; Maeda, Katsuhiro; Mizuno, Motohiro; Swager, Timothy M. (January 2018, RSC Advances)

   We have succeeded in developing triptycene-based chiral stationary phases with a distorted cyclic structure, which can resolve a series of axially chiral compounds. 

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3. Hydroxy sulfonic acid catalyzed hydrolysis of cellulose

   https://doi.org/10.1080/17597269.2023.2221969  

   Amarasekara, Ananda S.; Nwankwo, Victor C.; Fernando, Harshica (June 2023, Biofuels)

   Development of efficient catalytic methods for the hydrolysis of cellulose is a major research challenge in sustainable biofuel and polymer areas. In this study five hydroxy sulfonic acids were studied as simple model compounds for cellulase enzyme for the hydrolysis of cellulose. The catalytic activities were measured by analysis of total reducing sugar (TRS) yields produced in a series of reactions carried out at 150–190 °C using 0.050 M aqueous hydroxy sulfonic acid solutions. The highest catalytic activity was observed with isethionic acid, producing 62.7% TRS yield at 180 °C after 4 hr. In the second phase of the work, Density Functional Theory (DFT) calculations were used to study the interactions between hydroxy sulfonic acids and cellulose model compound D-cellobiose to supplement the experimental results. The D-cellobiose – hydroxy sulfonic binding energies and the distance between glycosidic oxygen and -SO3H acidic H were evaluated and the -SO3H to glycosidic oxygen distance was identified as the more important parameter co-related to the catalytic activity. The isethionic acid with highest cellulose hydrolysis activity showed the shortest -SO3H to glycosidic oxygen distance of 1.744 Å. 

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4. Synthesis and Self-Assembling Properties of Peracetylated β-1-Triazolyl Alkyl D-Glucosides and D-Galactosides

   https://doi.org/10.3390/chemistry3030068  

   Sharma, Pooja; Chen, Anji; Wang, Dan; Wang, Guijun (September 2021, Chemistry)

   Carbohydrate-based low-molecular-weight gelators (LMWGs) are useful classes of compounds due to their numerous applications. Among sugar-based LMWGs, certain peracetylated sugar beta-triazole derivatives were found to be effective organogelators and showed interesting self-assembling properties. To further understand the structural influence towards molecular assemblies and obtain new functional materials with interesting properties, we designed and synthesized a library of tetraacetyl beta-1-triazolyl alkyl-D-glucosides and D-galactosides, in which a two or three carbon spacer is inserted between the anomeric position and the triazole moiety. A series of 16 glucose derivatives and 14 galactose derivatives were synthesized and analyzed. The self-assembling properties of these new triazole containing glycoconjugates in different solvents were analyzed. Several glucose derivatives were found to be effective LMWGs, with compound 7a forming gels in a variety of organic solvents as well as in the presence of metal ions in aqueous solutions. The organogels formed by several compounds were characterized using optical microscopy, atomic force microscopy (AFM) and UV-vis spectroscopy, etc. The co-gels formed by compound 7a with the Fmoc derivative 7i showed interesting fluorescence enhancement upon gelation. Several gelators were also characterized using powder X-ray diffraction and FT-IR spectroscopy. The potential applications of these sugar-based gelators for drug delivery and dye removal were also studied. 

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5. Lewis acid mediated allylation of vinyl diazonium ions by allylstannanes

   https://doi.org/10.1039/d4ob00254g  

   Rose, Benjamin J; Brewer, Matthias (May 2024, Organic & Biomolecular Chemistry)

   The Lewis acid mediated reaction of allyltributylstannane compounds with β-hydroxy-α-diazo carbonyls gives β-allyl-α-diazo carbonyl products in good yields. This reaction proceeds via a vinyl diazonium ion intermediate which is intercepted by the allylstannane nucleophile. Importantly, the diazo functional group is retained over the course of the reaction to give diazo-containing scaffolds with increased molecular complexity. Methallyltrimethylsilane also serves as a functional allyl transfer reagent in this reaction. 

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