A novel no-carrier-added submicromolar scale radiosynthesis of [S-methyl-14C]-florfenicol

In this paper is reported a novel reaction scheme for the no-carrier-added submicromolar scale radiosynthesis of [S-methyl-(14)C]-florfenicol that has been newly designed, developed and employed by us successfully. The [(14)C]-product was obtained in an overall radiochemical yield of 30% based on [(14)C]-methyl iodide taken for the reaction with a radiochemical purity of more than 96%. The specific activity of the product was ~50 mCi (1.85 GBq)/mmol. Chlorosulfonation of compound I was followed by sodium salt formation in situ and it was succeeded by the introduction of [(14)C]-methyl group by coupling with [(14)C]-CH3 I. Subsequently, the oxazolidin-2-one protecting group was opened up by a reaction with sulfuric acid in dioxane and later, the amino group was dichloroacetylated with methyl-2,2-dichloroacetate in triethylamine to obtain [S-methyl-(14)C]-florfenicol.

A facile synthesis of deuterium labeled 2,2-dimethyl-[2H6]-succinic acid and its anhydride

Deuterium labeled 2,2-dimethyl-[(2)H(6)]-succinic anhydride by a sequence of reactions involving Knoevenagel condensation of [(2)H(6)]-acetone with ethyl cyanoacetate in the presence of piperidine, Michael addition of cyanide, HCl hydrolysis, simultaneous decarboxylation, and subsequent dehydration using acetic anhydride in an overall yield of 34.23% based on [(2)H(6)]-acetone utilized in the reaction is reported. The title compounds were characterized and confirmed spectroscopically by Fourier transform infrared, (1) H-NMR, and Mass. The chemical purity as determined by HPLC was 99%. To the best of our knowledge, the synthesis of these specifically deuterium labeled compounds has not been reported so far.

A convenient photosynthesis of uniformly [¹⁴C]-labelled D-glucose, D-fructose and sucrose, and chemical synthesis of methyl-α-D-glucopyranoside ([U-¹⁴C]-glucose)

This paper describes a convenient procedure for the radiochemical preparation of d-[U-(14)C]-glucose, d-[U-(14)C]-fructose and [U-(14)C]-sucrose with high specific activity by photosynthesis using 'canna indica' leaf, [(14)C]-carbon dioxide and water in presence of light in a closed system. The [(14)C]-sugars formed were extracted, separated and then purified by paper chromatography. Further, the pure d-[U-(14)C]-glucose obtained was converted to methyl-α-d-glucopyranoside ([U-(14)C]-glucose) by glycosidation with methanol using (i) HCl, the conventional Fischer method (ii) heterogeneous organic cation exchange resin (Amberlite IR-120 (H(+))) and (iii) heterogeneous inorganic cation exchanged montmorillonites called metal M(+n)-monts. The results indicated that the latter in the form of Fe(+3)-montmorillonite gave a better yield ( 65%) as compared to others (40-56%). The radiochemical purity of the no-carrier added product was more than 98%. The product retained its specific activity as that of the starting material which is in the range of 250-300 mCi/mmole (9.25-11.1 GBq/mmole), suitable for use as a radiotracer in biochemical investigations.

The first example of catalytic N-oxidation of tertiary amines by tungstate-exchanged Mg-Al layered double hydroxide in water: a green protocol

A green process, using a recyclable tungstate-exchanged Mg-Al layered double hydroxide (LDH-WO4(2-)) heterogenised catalyst and aqueous H2O2 oxidant in water, leads to N-oxidation of aliphatic tert-amines to amine N-oxides in quantitative yields, at a high rate at room temperature.