Home About us Contact
|
Home About us Contact | ||
|
|
||
Ring Portion (ring + portion)
Selected AbstractsSynthesis and Qualitative Olfactory Evaluation of Benzodioxepine AnaloguesHELVETICA CHIMICA ACTA, Issue 5 2007Britta Drevermann Abstract Marine fragrances, particularly Calone 1951® (=7-methyl-2H -1,5-benzodioxepin-3(4H)-one; 1) has carved a minor but distinct niche in the broad field of fragrance chemistry. By focusing on the polar structure fragment of the benzodioxepinone parent compound, we set out to determine the molecular influence on the dominant marine note attributed to the Calone 1951® structure. A selection of one-step modifications of the ketone 1 resulted in a range of odor-active conformers with diverse olfactory attributes. The synthesis of a range of benzodioxepine analogues, i.e., of 3,11, is presented alongside olfactory evaluation (Tables 2 and 3). Removal of the carbonyl group of 1 and increasing the size of the aliphatic ring portion (see 6 and 7) introduced sweetness and a predominant loss of the marine character. [source] Gas-phase fragmentation study of novel synthetic 1,5-benzodiazepine derivatives using electrospray ionization tandem mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2008Mohamed Rida The fragmentation patterns of a series of three novel synthesized 3-hydroxy-4-phenyl-tetrahydro-1,5-benzodiazepin-2-ones (1,3), possessing the same backbone structure, were investigated using electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) techniques. A simple methodology, based on the use of ESI (positive ion mode) and by increasing the declustering potential in the atmospheric pressure/vacuum interface, collision-induced dissociation (CID), was used to enhance the formation of the fragment ions. In general, the novel synthetic 1,5-benzodiazepine derivatives afforded, in the gas phase, both protonated and sodiated molecules. This led to the confirmation of the molecular masses and chemical structures of the studied compounds. Exact accurate masses were measured using a high-resolution ESI-quadrupole orthogonal time-of-flight (QqToF)-MS/MS hybrid mass spectrometer instrument. The breakdown routes of the protonated molecules were rationalized by conducting low-energy collision CID-MS/MS analyses (product ion- and precursor ion scans) using a conventional quadrupole-hexapole-quadrupole (QhQ) tandem mass spectrometer. All the observed major fragmentations for the 1,5-benzodiazepines occurred in the saturated seven-membered ring containing the nitrogen atoms. These formed a multitude of product ions by different breakdown routes. All the major fragmentations involved cleavages of the N -1,C -2 andC -3,C -4 bonds. These occurred with concomitant eliminations of glyoxal, benzene and ethyl formate, forming the product ion at m/z 119, which was observed in all the studied compounds. In addition, an unique simultaneous CID-MS/MS fragmentation was noticed for the 1,5-benzodiazepines 1 and 3, which occurred by a pathway dictated by the substituent located on the N -1-position. It was evident that the aromatic ring portion of the 1,5-benzodiazepines was resistant to CID-MS/MS fragmentation. Re-confirmation of the various geneses of the product ions was achieved by conducting a series of precursor ion scans. ESI-MS and CID-MS/MS analyses have thus proven to be a specific and very sensitive method for the structural identification of these novel 1,5-benzodiazepine derivatives. Copyright © 2008 John Wiley & Sons, Ltd. [source] 4-(9,10-Dihydroacridin-9-ylidene)thiosemicarbazide and its five-membered thiazole and six-membered thiazine derivativesACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2010Ivan Poto Two methyl derivatives, five-membered methyl 2-{2-[2-(9,10-dihydroacridin-9-ylidene)-1-methylhydrazinyl]-4-oxo-4,5-dihydro-1,3-thiazol-5-ylidene}acetate, C20H16N4O3S, (I), and six-membered 2-[2-(9,10-dihydroacridin-9-ylidene)-1-methylhydrazinyl]-4H -1,3-thiazin-4-one, C18H14N4OS, (II), were prepared by the reaction of the N -methyl derivative of 4-(9,10-dihydroacridin-9-ylidene)thiosemicarbazide, C14H12N4S, (III), with dimethyl acetylenedicarboxylate and methyl propiolate, respectively. The crystal structures of (I), (II) and (III) are molecular and can be considered in two parts: (i) the nearly planar acridine moiety and (ii) the singular heterocyclic ring portion [thiazolidine for (I) and thiazine for (II)] including the linking amine and imine N atoms and the methyl C atom, or the full side chain in the case of (III). The structures of (I) and (II) are stabilized by N,H...O hydrogen bonds and different ,,, interactions between acridine moieties and thiazolidine and thiazine rings, respectively. [source] Lenalidomide, an antineoplastic drug, and its hemihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Krishnan Ravikumar The crystal structures of lenalidomide [systematic name: (RS)-3-(4-amino-1-oxoisoindolin-2-yl)piperidine-2,6-dione], C13H13N3O3, (I), an antineoplastic drug, and its hemihydrate, C13H13N3O3·0.5H2O, (II), have been determined by single-crystal X-ray diffraction analysis. The overall conformation of the molecule defined by the orientation of the two ring portions, viz. pyridinedione and isoindolinone, is twisted in both structures. The influence of the self-complementary pyridinedione ring is seen in the crystal packing of both structures through its involvement in forming hydrogen-bonded dimers, although alternate dione O atoms are utilized. An extensive series of N,H...O hydrogen bonds link the dimers into two-dimensional supramolecular arrays built up from infinite chains. The water molecule in (II) has a cohesive function, connecting three lenalidomide molecules by hydrogen bonds. The significance of this study lies in the analysis of the interactions in these structures and the aggregations occurring via hydrogen bonds in the hydrated and dehydrated crystalline forms of the title compound. [source] | ||||||||||