Metal-Catalyzed Site-Selective Monoacylation of Diols in Aqueous Media

Site-selective reactions of water-soluble biomolecules are being developed to produce efficient conversions in water and water­/solvent mixtures. This review focuses on the use of designs based on bis-bidentate chelation of large metal ions by diols to be acylated by a co-chelated water-stable reagent. Topics discussed include: 1. The preparation and properties of water-stable acyl phosphate monoesters and their reactions with diol-chelated metal ions. 2. Site-selective monoaminoacylation of 3′-terminal diols of RNA and their applications in protein engineering. 3. Site-selective monoacylation of sugars with acyl phosphate monoesters associated with metal ions, including lanthanum and lead. The combination of metal ion, 1,2-diol, and acyl phosphate monoester produces site-selective reactions in aqueous media­ that can produce a general approach to site-selective mono-(amino)acylation in RNA and carbohydrates.1 Introduction2 Synthetic Aminoacylation of tRNA3 Activated Amino Acids in Water4 Metal Ions and Their Effects on the Reactivity of Acyl Phosphate Monoesters5 The Challenge of Site-Selective Acylation of Carbohydrates in Water6 Conclusions and Prospects

Gold(i)-catalyzed Nicholas reaction with aromatic molecules utilizing a bifunctional propargyl dicobalt hexacarbonyl complex

A benchtop-stable reagent for the catalytic Nicholas reaction with aromatic molecules was developed.

Effect of flow switch on two phase flow evenness based on granular magnesium

The aim of the work was to study, with the help of a laboratory setup, the influence of the existing design of the flow switch on the uniformity of movement of a two-phase flow, consisting of granular magnesium and compressed gas. On the basis of a typical layout of injection systems for the injection of granular magnesium at the pig iron desulphurization plants in the ladles, a laboratory installation has been created that allows the generation of a stable uniform flow of granular magnesium in a stream of compressed air. The stream was passed through a transparent full-scale model of a standard unit for switching the flow into three lances, while the angle of inclination of the device itself, the flow switch, changed. The process was recorded by video. The frame-by-frame analysis of the video image made it possible to study the effect of the existing design of the flow switch at different angles of inclination on the uniformity of the movement of the two-phase flow along the path of the injection system during ladle desulfurization of the molten iron with granular magnesium. The presented studies made it possible to establish the main causes and reveal the mechanism of the generation of pulsations in the cavity of the studied node of the flow switch. It is shown that the volume of the switch cavity contributes to the accumulation of magnesium in it and when tilting more than 22° to the horizon, spontaneous pouring of the accumulated magnesium in the cavity occurs, which is the main reason for the occurrence of pulsations. The recommendations developed on the basis of the research results and their implementation on the existing cast iron desulfurization unit in 100 ton buckets of the new steel plant of the Qingdao Steel Plant (Qingdao, PRC, 2016) made it possible to reduce roughness during processing and ensure stable reagent injection with a double intensity.

New Avenues in Radical Trifluoromethylselenylation with ­Trifluoromethyl Tolueneselenosulfonate

We demonstrated that the shelf-stable reagent trifluoromethyl tolueneselenosulfonate can be involved in radical trifluoromethylselenylation. Upon visible-light irradiation, the homolysis of the reagent could take place at room temperature. This finding is explored for unprecedented C(sp2)–SeCF3 and C(sp3)–SeCF3 processes under transition-metal-free conditions. Mechanistic investigations, including cyclic voltammetry, luminescence measurement, and EPR studies, allowed the proposal of plausible mechanisms.1 Introduction.2 Reactivity of Reagent I with Diazonium Salts3 Reactivity of Reagent I with Alkenes and Alkynes4 Conclusion

Visible-Light-Mediated Synthesis of Trifluoromethylthiolated Arenes

The visible-light-mediated synthesis of trifluoromethylthiolated arenes in the presence of ruthenium-based photocatayst under mild reaction conditions is reported. The trifluoromethylthiolated arenes are obtained using the shelf-stable reagent trifluoromethyl toluenethiosulfonate at room temperature. The reaction proceeds selectively and does not require the presence of any additive. A mechanism is proposed based on the obtained results of EPR as well as luminescence

Visible light-promoted difluoromethylthiolation of aryldiazonium salts

Difluoromethylthiolation of aryldiazonium salts under mild conditions using a shelf-stable reagent (PhSO2SCF2H) was reported.

1,3-Dibromo-5,5-dimethylhydantoin as promoter for glycosylations using thioglycosides

1,3-Dibromo-5,5-dimethylhydantoin (DBDMH), an inexpensive, non-toxic and stable reagent, is a competent activator of thioglycosides for glycosidic bond formation. Excellent yields were obtained when triflic acid (TfOH) or trimethylsilyl trifluoromethanesulfonate (TMSOTf) were employed as co-promoters in solution or automated glycan assembly on solid phase.