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Spin diffusion in NMR occurs for small- and medium-sized molecules when their tumbling rate reduces in solution so that magnetization exchange by longitudinal cross relaxation becomes highly efficient. Composite DMSO-water viscous solvents were used for the first time to access the individual NMR spectra of a mixture components in spin diffusion conditions. The easy handling and high dissolution power of [D 6 ]DMSO/H 2 O offers a wide range of potential applications for polar and moderately apolar mixture analysis. In addition to 2D 1 H- 1 H NOESY and 1 H- 13 C HSQC-NOESY, 1 H- 15 N HSQC-NOESY, 1D and 2D 1 H- 19 F heteronuclear NOESY (HOESY) experiments were set up to offer new ways to individualize molecules within a mixture. This article reports the analysis of a polar mixture of four dipeptides dissolved in [D 6 ]DMSO/H 2 O (7:3 v/v) and that of a medium-polarity fluorinated dinucleotide dissolved in [D 6 ]DMSO/H 2 O (8:2 v/v) by means of spin diffusion in NOESY, HOESY, and HSQC-NOESY experiments., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The stereo- and regioselectivity of triplet-sensitised radical reactions of furanone derivatives have been investigated. Furanones 7a,b were excited to the (3)pipi* state by triplet energy transfer from acetone. Intramolecular hydrogen abstraction then occurred such that hydrogen was transferred from the tetrahydropyran to the beta position of the furanone moiety. Radical combination of the tetrahydropyranyl and the oxoallyl radicals led to the final products 8a,b. In the intramolecular reaction, overall, a pyranyl group adds to the alpha position of the furanone. The effect of conformation was first investigated with compounds 9a,b carrying an additional substituent on the tether between the furanone and pyranyl moiety. Further information on the effect of conformation and the relative configuration at the pyranyl anomeric centre and the furanone moiety was obtained from the transformations of the glucose derivatives 12, 14, 17 and 18. Radical abstraction occurred at the anomeric centre and at the 5'-position of the glucosyl moiety. Computational studies of the hydrogen-abstraction step were carried out with model structures. The activation barriers of this step for different stereoisomers and the abstraction at the anomeric centre and at the 6'-position of the tetrahydropyranyl moiety were calculated. The results of this investigation are in accordance with experimental observations. Furthermore, they reveal that the reactivity and regioselectivity are mainly determined in the hydrogen-abstraction step. Intramolecular hydrogen abstraction (almost simultaneous electron and proton transfer) in (3)pipi* excited furanones only takes place under restricted structural conditions in a limited number of conformations that are defined by the relative configuration of the substrates. It is observed that in the biradical intermediate, back-hydrogen transfer occurs leading to the starting compound. In the case of glucose derivatives, this reaction led to epimerisation at the anomeric centre.

The purification of p-hydroxybenzylglucosinolate (sinalbin) on a multigram scale from a crude aqueous extract of white mustard seeds (Sinapis alba var. concerta) was successfully achieved by scaling up a strong ion-exchange centrifugal partition chromatography (SIXCPC) laboratory procedure. Thus, the one-step sinalbin purification was performed with 2.35 g of crude extract in approximately 170 min (830 mg/h) up to 70.3 g in approximately 160 min (26.3 g/h) by switching from a 200 mL laboratory scale column to a 5.7 L pilot-scale column. The required biphasic solvent system contained ethyl acetate, n-butanol, and water in 3:2:5 v/v/v proportions, Aliquat 336 (trioctylmethyl ammonium chloride) was added to the organic stationary phase (80 mM) and acted as ion-exchanger. Potassium iodide in the aqueous mobile phase (80 mM) was used as sinalbin displacer. The 28.5 mass scale factor arose from the increase in mobile phase flow-rate (from 2 to 50 mL/min), from the higher mass of injected white mustard seed extract (from 12 to 350 g), and from the calculated productivity (from 830 mg to 26.3 g). These results demonstrate that industry scale production of glucosinolates is easily performed by SIXCPC, thus providing pure reference standards for pharmacology studies.