Improvement in flow-sheet of extraction chromatography for trivalent minor actinides recovery

Journal of Radioanalytical and Nuclear Chemistry - Extraction chromatography flow-sheet employing octyl(phenyl)-N,N-diisobutylcarbonoylmethylphosphine oxide and bis(2-ethylhexyl) hydrogen phosphate...     

Direct Addition of Amides to Glycals Enabled by Solvation‐Insusceptible 2‐Haloazolium Salt Catalysis

The direct 2‐deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2‐deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2‐deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2‐deoxyglycosylation of amide groups using a newly designed Brønsted acid catalyst under mild conditions. Through mechanistic investigations, we discovered that the amide group can inhibit acid catalysts, and the inhibition has made the 2‐deoxyglycosylation reaction difficult. Diffusion‐ordered two‐dimensional NMR spectroscopy analysis implied that the 2‐chloroazolium salt catalyst was less likely to form aggregates with amides in comparison to other acid catalysts. The chlorine atom and the extended π‐scaffold of the catalyst played a crucial role for this phenomenon. This relative insusceptibility to inhibition by amides is more responsible for the catalytic activity than the strength of the acidity.     

General Formation of Macro-/Mesoporous Nanoshells from Interfacial Assembly of Irregular Mesostructured Nanounits

Mesoporous core–shell nanostructures with controllable ultra-large open channels in their nanoshells are of great interest. However, soft template-directed cooperative assembly to mesoporous nanoshells with highly accessible pores larger than 30 nm, or even above 50 nm into macroporous range, remains a significant challenge. Herein we report a general approach for precisely tailored coating of hierarchically macro-/mesoporous polymer and carbon shells, possessing highly accessible radial channels with extremely wide pore size distribution from ca. 10 nm to ca. 200 nm, on diverse functional materials. This strategy creates opportunities to tailor the interfacial assembly of irregular mesostructured nanounits on core materials and generate various core–shell nanomaterials with controllable pore architectures. The obtained Fe,N-doped macro-/mesoporous carbon nanoshells show enhanced electrochemical performance for the oxygen reduction reaction in alkaline condition.     

Extending the possibility of an N-Troc-protected sialic acid donor toward variant sialo-glycoside synthesis

The potential of an N-Troc-protected sialic acid donor, equipped with phenylsulfenyl functionality as a leaving group, has been explored. As a result, the entitled donor was proven to be highly reactive and to have broad applicability toward the synthesis of variant sialo-glycans, which have N-glycolyl, de-N-acetyl, 1,5-lactam and 8-O-sulfo sialic acid analogs.     

(Triisopropylsilyl)acetaldehyde acetal as a novel protective group for 1,2-diols

(Triisopropylsilyl)acetaldehyde dimethyl acetal (TIPS-ADMA) was synthesized from chlorotriisopropylsilane in three steps. Cyclic and acyclic 1,2-diols can be transformed to (triisopropylsilyl)ethylidene acetals (TIPS-AA). Removal of the acetal by LiBF₄ regenerates the starting diol in excellent yield even in the presence of an acetonide of 1,2-diol. The TIPS-AA group can survive under the deprotection conditions of the acetonide in acetic acid at 80 °C. Selective protection of 2,3- and 4,6-diols for O-methyl d-mannoside with TIPS-ADMA and selective deprotection of the acetals have been achieved.     

Gelation in free-radical terpolymerization of poly(allyl methacrylate) crosslinked polymer nanosphere with allyl benzoate and vinyl benzoate

Microgel-like poly(allyl methacrylate) (PAMA nanosphere) was prepared by the emulsion polymerization of AMA as the reactive crosslinked polymer nanosphere with abundant pendant allyl groups. The terpolymerization of PAMA nanosphere with allyl benzoate (ABz) and vinyl benzoate (VBz) was conducted in bulk using benzoyl peroxide as initiator at 80 °C. The gelation depended on the feed ABz/VBz molar ratio since the molecular weights of resulting poly(ABz-co-VBz)s that act as the bridges increased with an increase in the mole fraction of VBz in the feed monomer. Beyond the gel point, the sol was rapidly incorporated into the gel and the increasing tendency of the gel fraction became steeper from 70 to 95 mol% of VBz as a reflection of increased chain length of bridge between PAMA nanospheres. Moreover, the swelling ratio became lower with increasing the mole percentage of VBz in the feed monomer. These results would support the preferential incorporation of PAMA nanosphere into the gel and the longer bridge can capture more nanospheres to give a much shrunken gel.     

Transformation of Cinchona alkaloids into 1-N-oxide derivatives by endophytic Xylaria sp isolated from Cinchona pubescens

The microbial transformation of four Cinchona alkaloids (quinine, quinidine, cinchonidine, and cinchonine) by endophytic fungi isolated from Cinchona pubescens was investigated. The endophytic filamentous fungus Xylaria sp. was found to transform the Cinchona alkaloids into their 1-N-oxide derivatives.     

A total synthesis of spiruchostatin A

We achieved the total synthesis of the histone deacetylase inhibitor spiruchostatin A, as the prelude to the preparation of a combinatorial library of its analogues. Two key reactions were an asymmetric acetate aldol reaction using a Zr-enolate and macrolactonization using the Shiina method.     

Mössbauer spectrometica analysis of thermal decomposition products of phosphate and oxalate coatings on steel

The deterioration of zinc, zinc—calcium and manganese phosphate coatings and oxalate coatings on steel on heating was investigated by conversion electron Mössbauer spectrometry. and the chemical change of the coatings was analysed on the basis of the thermal characteristics of Zn₃(PO₄)₂·4H₂O, Zn₂Fe(PO₄)₄·4H₂O, CaZn₂(PO₄)₂·2H₂O, Fe₃(PO₄)₂·8H₂O. (Mn, Fe)₅H₂(PO₄)₄·4H₂O and FeC₂O₄·2H₂O. The steel substrate beneath the coatings influenced the thermal decomposition and evaporation of coating materials under the various heating atmospheres. The heat resistance of these coatings and the state of the substrate were also investigated.