A convenient two-step preparation of monodeuteriated tetramethylsilane

Purified partially mono-deuteriatedTMS was synthesized by preparing lithiomethyltrimethylsilane from chloromethyltrimethylsilane and reaction of the former with deuteriated water. Using this reference deuterium chemical shifts in parts per million can be reported with respect to [²H] resonance frequency of internalTMS in deuterium nmr spectroscopy.

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Eine einfache zweistufige Synthese von monodeuteriertem Tetramethylsilan (Kurze Mitteilung)

Zusammenfassung Es wird die Synthese von partiell monodeuteriertemTMS beschrieben. Dazu wurde Monochlormethyltrimethylsilan in Lithiomethyltrimethylsilan übergeführt und dieses mit D₂O weiter zum Zielprodukt umgesetzt.

     

Development of a sensitive MEKC-LIF method for synthetic cathinones analysis

Synthetic cathinones are phenylalkylamine compounds related to natural cathinone from Catha edulis leaves. Due to their sympathomimetic effects comparable to common illicit drugs, these substances are mainly drugs of abuse and constitute the second most frequently seized group of new psychoactive substances. In order to ensure their regulation and to promote public health, reliable analytical tools are required to track these substances. In the present study, we developed a CE hyphenated to laser-induced fluorescence detection method to demonstrate its suitability to perform fast and cost-effective synthetic cathinones analysis. Fourteen compounds including isobaric compounds and position isomers were selected to encompass the large panel of chemical structures. To separate the FITC-labeled analytes (presenting the same negative charge and close mass to charge ratios), MEKC separation mode was selected. Method selectivity was not suitable using common surfactants. In this context, alkyl polyethylene glycol ether surfactants were successfully used as neutral surfactant to overcome this analytical challenge. The effect of surfactant nature on separation performances and migration behaviors of the analytes was also studied. Optimal BGE composition included 75 mM borate buffer at pH 9.3 and 0.4 mM of C12E10 surfactant. Final MEKC separation conditions were proposed to analyze a large panel of synthetic cathinones. This method helped to reach a sensitivity with LOD from 0.1 to 0.4 nM (pg/mL order).     

A two-step preparation of aristolne from calarene.

A two-step isomerization scheme based on an ene-reaction with the readily available PhSO₂NSO and then desulphuration with Raney nickel/hydrogen leads to aristolene from calarene.     

A method for the preparation of corchoroside A

Chemistry of Natural Compounds -     

A two-step procedure for the preparation of mono-protected bis-N-heterocyclic alkyl ether systems

A two-step convenient sequence for the synthesis of previously inaccessible mono-Boc-protected bis-N-heterocyclic alkyl substituted ether derivatives 4 is described. Mitsunobu protocol was applied to the preparation of pyridinyl ether precursor 5. The reduction of the electron rich pyridinyl system 5 has been achieved catalytically using the combination of PtO₂-H₂SO₄ or PtO₂-pTsOH under a hydrogen atmosphere maintained by a gas balloon at ambient temperature.     

A method for preparation of C-diformylmethylnitropyrazoles

Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 230–231, January, 1993.     

A method for the preparation of terminal acetylenes

A new pathway is proposed for the preparation of terminal acetylenes entailing the condensation of acid chlorides with phenylacetylene, isomerization of the acetylenic ketones with displacement of the oxo group and triple bond in the ketoacetylenic fragment, and subsequent alkaline cleavage of the isomerized ketones.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2622–2624, November, 1990.     

A new method for the preparation of polyfluoroalkanedithiocarboxylates

A new method for synthesis of alkyl and aryl polyfluoroalkyldithiocarboxylates by reaction of 1,1-dichloropolyfluoroalkylsulfenylchlorides with mercaptans in the presence of ZnCl₂ was developed. The sulfenylchlorides are easily obtained by chlorination of benzyl 1,1-dihydropolyfluoroalkylsulfides or benzyl dithioacetals of polyfluoroaldehydes.     

A two-step extraction method for differentiating chromium species in water

The hexavalent Cr species Cr(VI) in natural waters can be quantitatively extracted by diethyldithiocarbamate (DDTC) in the pH range 4.0–4.5 into chloroform, followed by back-extraction into a Hg(II) solution for graphite furnace atomic absorption spectrometry (GFAAS). The trivalent Cr(III) species can be oxidized to Cr(VI) by KMnO₄ and then extracted by the DDTC-Hg(II) procedure. The proposed two-step extraction method combined with GFAAS is suitable for Cr speciation studies in natural water systems.     

A new method for the preparation of perfluorocarboxylic acids

The reaction of both primary perfluoroalkyl iodides and bromides containing 3 ∼ 12 carbon atoms [CF₃(CF₂)_nX, n = 2 ∼ 11, X = Br, I] with a Rongalite-NaHCO₃ reagent in aqueous dipolar aprotic solvents, such as DMF or DMSO, has been investigated. The reaction gave sodium perfluorocarboxylates [CF₃(CF₂)_n-1CO₂Na, n = 2 ∼ 11] in 51 – 86 % yields, and these were transformed to the respective perfluorocarboxylic acids [CF₃(CF₂)_n−1CO₂H, n = 2 ∼ 11] by treatment with sulfuric acid. This provides a new method for the synthesis of perfluorocarboxylic acids.     

A new method for the preparation of diphenylmethyl ethers

Various diphenylmethyl ethers are prepared under mild conditions by using tri-diphenylmethyl phosphate as alkylating agent. O-Diphenylmethyl-L(?)-Lactic Acid is prepared by this method.     

A simple method for the preparation of pure hafnium

The separation of zirconium and hafnium by fractional precipitation as pyrophosphate¹ has been extended for the preparation of pure hafnium. The favourable uptake of hafnium, in spite of the decreasing tendency of partition factor when hafnium concentration is high, is maintained for all concentration of hafnium (relative to zirconium). Particularly significant is the fact that at very high concentrations of hafnium (at≈84%) the uptake of zirconium sharply falls. So pure hafnium can be prepared from natural zirconium by a simple process of eight or nine stages of fractional precipitations as pyrophosphate. This process yields reactor grade zirconium on the one side and pure hafnium on the other side.     

A general method for the preparation of perfluoroalkanesulfonyl chlorides

A mild two-step synthesis of perfluoroalkanesulfonyl chlorides starting from perfluoroalkyl iodides has been developed. Reaction of perfluoroalkyl iodides with sodium dithionite gave sodium perfluoroalkanesulfinate salts which were converted into perfluoroalkanesulfonyl chlorides in 25-73% yield (two steps) using N-chlorosuccinimide.     

A new method for the preparation of modified oligonucleotides

[reaction-see text] N-Nitrothymidine can be transformed into a phosphoramidite building block suitable for oligonucleotide synthesis using the standard phosphite triester solid-phase approach. The N-nitrothymidine residues remain stable during the elongation cycles and react smoothly with primary amines, furnishing oligonucleotides containing N3-modified thymidines. A number of N3-substituted oligonucleotides have been prepared using this methodology, some of them incorporating aminoalkyl or hydroxyalkyl groups.     

A new general method for the preparation of N-sulfonyloxaziridines

[reaction: see text] A simple procedure to obtain N-alkylsulfonyl- and N-arylsulfonyloxaziridines from the corresponding N-sulfinylimines involving a one-pot, two-step oxidation process with m-CPBA (1 equiv) and m-CPBA/KOH (1.1 equiv) is reported. The method is applicable to N-sulfinylimines derived from aldehydes (aliphatic and aromatic) and ketones (dialkyl and aryl alkyl) and preserves C=C-conjugated double bonds. Almost quantitative yields, very mild conditions (usually less than 5 min at room temperature), and easy purification by filtration are the main features of this new procedure, which can be performed at a gram scale.