PubMed · 13663680
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1959-04-09. [Nitrofurans].. https://pubmed.ncbi.nlm.nih.gov/13663680/
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The synthesis of a stereoisomer library of 16 murisolins in individual pure form by fluorous mixture synthesis is reported. Four stereoisomeric precursors are tagged with different fluorous tags, and the resulting mixture is taken through the synthesis with four splits and late stage demixing and detagging to give all 16 products. These products exhibit only six different sets of NMR spectra, but all can be differentiated by chiral HPLC. The structure of murisolin is confirmed, but the structures of murisolin A and 16,19-cis-murisolin may never be known with certainty because insufficient data were collected on natural samples to differentiate each of them from one other isomer.
We report the theoretical validation of the experimentally observed structure-activity relationships (SAR) of a set of N-substituted 4-amino-3,3-dialkyl-2(3H)-furanone GABA receptor modulators showing positive allosteric modulatory activity of the GABA(A) receptor similar to that shown by Loreclazole. Efforts were made to explain some of the conclusions drawn during this study based on a solitary instance of occurrence of the observation within the dataset. Some of the conclusions selected for study included (i) the enhanced activity for the R enantiomer of a compound, (ii) enhanced activity for a compound with an amide type functionality vis-à-vis an amine type functionality at C-4, (iii) enhanced activity for a compound with a carboxamide or carbamate type functionality linking the end group at C-4 over a compound with only the end group attached, provided the alkyl groups attached at C-3 are identical in both cases. The 3-D-QSAR method of molecular field analysis along with receptor-ligand complex stability studies were found to be the most suitable for explaining these activities. While the first conclusion was comprehensively proven, significant support was obtained in case of the latter two. Further comprehensive study is underway and we hope to report them shortly.
A method for the analytical determination of sotolon [4,5-dimethyl-3-hydroxy-2(5H)-furanone], maltol [3-hydroxy-2-methyl-4H-pyran-4-one] and free furaneol [2,5-dimethyl-4-hydroxy-3(2H)-furanone] in wine has been developed. The analytes are extracted from 50 ml of wine in a solid-phase extraction cartridge filled with 800 mg of LiChrolut EN resins. Interferences are removed with 15 ml of a pentane-dichloromethane (20:1) solution, and analytes are recovered with 6 ml of dichloromethane. The extract is concentrated up to 0.1 ml and analyzed by GC-ion trap MS. Maltol and sotolon were determined by selected ion storage of ions in the m/z ranges 120-153 and 79-95, using the ions m/z 126 and 83 for quantitation, respectively. Furaneol was determined by non-resonant fragmentation of the m/z 128 mother ion and subsequent analysis of the m/z 81 ion. The detection limits of the method are in all cases between 0.5 and 1 microg l(-1), well below the olfactory thresholds of the compounds. The precision of the method is in the 4-5% range for levels in wine around 20 microg l(-1). Linearity holds at least up to 400 microg l(-1), and is satisfactory in all cases. The recoveries of maltol and sotolon are constant (70 and 64%, respectively) and do not depend on the type of wine. On the contrary, in the case of furaneol, red wines show constant and high recoveries (97%), while the recoveries on white wines range between 30 and 80%. Different experiments showed that this behavior is probably due to the existence of complexes formed between furaneol and sulphur dioxide or catechols. Sensory experiments confirmed that the complexed forms found in white wines are not perceived by orthonasal olfaction, and that the furaneol determined by the method can be considered as the free and odor-active fraction.