0000000000988078
AUTHOR
Vladimir V. Ovcharenko
A correlative IR, MS, 1H, 13C and 15N NMR and theoretical study of 4-arylthiazol-2(3H)-onesElectronic supplementary information (ESI) available: NMR data, including graphs; Cartesian coordinates for 3a and 4. See http://www.rsc.org/suppdata/p2/b1/b106322g/
Sixteen 4-arylthiazol-2(3H)-ones (3) were synthesised by cyclisation of α-thiocyanatoacetophenones (1) in acid solution. They appear to prefer greatly the oxo tautomeric forms. In CCl4 solution an equilibrium between the free CO bond and a “dimeric” hydrogen-bonded form exists in which the latter predominates. Several IR and NMR (1H, 13C and 15N) spectral properties are shown to correlate with Hammett σ-values and/or atomic Mulliken charges and bond orders, the latter being estimated by PM3 or AM1 semiempirical methods. The electron-impact mass spectra were also recorded and the fragmentation mechanisms interpreted in terms of the energetics of the ionic species. In addition, the geometric …
Frankiamide: A Structural Revision to Demethyl (C-11) Cezomycin.
A compound (née frankiamide) isolated from Frankia was initially structurally elucidated on the basis of NMR and MS. However, X-ray analysis provided a structure that is in discord with this structure and in light of this the structure has now been revised and the compound renamed as demethyl (C-11) cezomycin.
Synthesis and structural characterization of cis- and trans-fused 4a,5,6,7,8,8a-hexahydro-2H,4H-1,3-benzodithiines and their 2-methyl and 2,2-dimethyl derivatives.
Both cis- and trans-fused 4a,5,6,7,8,8a-hexahydro-2H,4H-1,3-benzodithiine together with their 2-methyl and 2,2-dimethyl derivatives were prepared as racemates from the appropriate dithiols obtained via multistep syntheses. The products were characterized by 1 H and 13 C NMR, mass spectrometry, and for two of the cis-fused compounds by X-ray diffraction. 1 H, 1 H vicinal coupling constants indicated that all compounds attain chair-chair conformations as their predominant conformations. All three trans-fused isomers exist in totally biased chair-chair conformations and are essentially conformationally locked, whereas the cis-fused compounds are conformationally mobile and can potentially atta…
Synthesis and NMR characterization of the cis and trans isomers of [Pt(II)(N9-adeH)2(pz)2] and X-ray crystallography of the trans isomer.
The reaction of tetrapyrazine Pt(II) with adenine under basic conditions yielded two products both disubstituted by adenine and bound in all cases to the N-9 nitrogen of adenine. Crystals amenable to X-crystallographic analysis were obtained for one product which was consequently identified as trans-[Pt(II)(N9-adeH)2(pz)2](NO3)(4).H2O. The other product, though, was identified as the cis isomer based on extensive and comparative NMR structural studies whereby the two compounds were examined as both neutral and tetraprotonated species in solution. The major product of the reaction was unexpectedly the cis isomer, thus obtained in contrast to the trans effect, and the reason for this result i…