An efficient protocol for the rapid room temperature deacetylation of carbohydrate derivatives using CuFe 2 O 4 nanoparticles as an inexpensive and reusable catalyst is presented. After separation of the catalyst with an external magnet, the reaction products are easily obtained in good purity and excellent yields.
The partition coefficients, P(IL/w), for different probe molecules as well as for compounds of biological interest between the room-temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMIM][PF(6)], 1-hexyl-3-methylimidazolium hexafluorophosphate, [HMIM][PF(6)], 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF(4)] and water were accurately measured. [BMIM][PF(6)] and [OMIM][BF(4)] were synthesized by adapting a procedure from the literature to a simpler, single-vessel and faster methodology, with a much lesser consumption of organic solvent. We employed the solvation-parameter model to elucidate the general chemical interactions involved in RTIL/water partitioning. With this purpose, we have selected different solute descriptor parameters that measure polarity, polarizability, hydrogen-bond-donor and hydrogen-bond-acceptor interactions, and cavity formation for a set of specifically selected probe molecules (the training set). The obtained multiparametric equations were used to predict the partition coefficients for compounds not present in the training set (the test set), most being of biological interest. Partial solubility of the ionic liquid in water (and water into the ionic liquid) was taken into account to explain the obtained results. This fact has not been deeply considered up to date. Solute descriptors were obtained from the literature, when available, or else calculated through commercial software. An excellent agreement between calculated and experimental log P(IL/w) values was obtained, which demonstrated that the resulting multiparametric equations are robust and allow predicting partitioning for any organic molecule in the biphasic systems studied.
Mass spectrometry is used to evaluate the occurrence of thio-enol structures among the several possible tautomers of thiohydantoins and dithiohydantoins. Mass spectra of differently substituted thiohydantoins are examined looking for common mass spectral behaviors. Ion fragmentations from specific tautomers allow to predict the most stable thio-enol structure for both type of compounds. The mass spectrum of the alkylation product of 5,5- dimethyldithiohydantoin and the nuclear magnetic resonance spectra of the alkylation products of both 2- thiohydantoin and dithiohydantoin support the fact that the most likely thio-enolstructure is determined by the presence of one or two thio-carbonyl groups in the hydantoin molecule.
Cu-Fe spinels promoted the Ferrier rearrangement of 2-nitroglycals with several
O-nucleophiles. 2,3-Unsaturated carbohydrate derivatives were prepared by the reaction of 3,4,6-tri-Oacetyl-
2-nitroglucal and alcohols in the presence of 5 % of CuFe2O4. After separation of the catalyst with
an external magnet, the reaction products were obtained in good yields and high stereo and regioselectivity.
Also, S- and heterocyclic C-3 substituted 2-nitro-endo-glycals could be prepared by this method.
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