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Thio Derivatives (thio + derivative)
Selected AbstractsChemInform Abstract: t-BuOK-Catalyzed Addition of Ketones and Nitriles to Vinylic Silanes, Phosphines and Thio Derivatives.CHEMINFORM, Issue 33 2001Tanasri Bunlaksananusorn Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A theoretical density functional study of association of Zn2+ with oxazolidine and its thio derivatives in the gas phaseJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2010Zaki S. Safi Abstract We have performed density functional theory (DFT) calculations in order to study the gas-phase interaction of oxo- and thio-oxazolidine derivatives with Zn2+. The calculations were performed at B3LYP/6-311+(2df,2p) level of theory. It has been found, in all cases, that the direct association of Zn2+ with the carbonyl and thiocarbonyl groups takes place at the heteroatom attached to position 2 irrespective of its nature. This preference has been attributed to the resonance effects caused by the nearest heteroatoms (oxygen and nitrogen). The most stable complexes correspond to structures with Zn2+ bridging between the heteroatom at position 2 or 4 of the 4- or 2-enol (or the 4- or 2-enethiol) tautomer and the dehydrogenated ring nitrogen atom, N3. Zn2+ association has a clear catalytic effect on the tautomerization processes which connect the oxo,thione forms with the enol,enethiol tautomers. Hence, although the enol,enethiol tautomers of oxazolidine and its thio derivatives should not be observed in the gas phase, the corresponding Zn2+ complexes are the most stable species and should be accessible, because the tautomerization barriers are smaller than the Zn2+ binding energies. Copyright © 2010 John Wiley & Sons, Ltd. [source] The influence of sulfur substituents on the molecular geometry and packing of thio derivatives of N -methylphenobarbitalACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Alicja Janik The room-temperature crystal structures of four new thio derivatives of N -methylphenobarbital [systematic name: 5-ethyl-1-methyl-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trione], C13H14N2O3, are compared with the structure of the parent compound. The sulfur substituents in N -methyl-2-thiophenobarbital [5-ethyl-1-methyl-5-phenyl-2-thioxo-1,2-dihydropyrimidine-4,6(3H,5H)-dione], C13H14N2O2S, N -methyl-4-thiophenobarbital [5-ethyl-1-methyl-5-phenyl-4-thioxo-3,4-dihydropyrimidine-2,6(1H,5H)-dione], C13H14N2O2S, and N -methyl-2,4,6-trithiophenobarbital [5-ethyl-1-methyl-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trithione], C13H14N2S3, preserve the heterocyclic ring puckering observed for N -methylphenobarbital (a half-chair conformation), whereas in N -methyl-2,4-dithiophenobarbital [5-ethyl-1-methyl-5-phenyl-2,4-dithioxo-1,2,3,4-tetrahydropyrimidine-6(5H)-one], C13H14N2OS2, significant flattening of the ring was detected. The number and positions of the sulfur substituents influence the packing and hydrogen-bonding patterns of the derivatives. In the cases of the 2-thio, 4-thio and 2,4,6-trithio derivatives, there is a preference for the formation of a ring motif of the R22(8) type, which is also a characteristic of N -methylphenobarbital, whereas a C(6) chain forms in the 2,4-dithio derivative. The preferences for hydrogen-bond formation, which follow the sequence of acceptor position 4 > 2 > 6, confirm the differences in the nucleophilic properties of the C atoms of the heterocyclic ring and are consistent with the course of N -methylphenobarbital thionation reactions. [source] | ||||||||||