Crystal structure of (E)-2-(1-methoxyimidazol-2-yl)- 2-oxoacetaldehyde O-methyl oxime, C7H9N3O3

Laus, Gerhard; Kahlenberg, Volker; Reischl, Wolfgang; Schottenberger, Herwig

doi:10.1524/ncrs.2011.0279

Cited by 2 publications

(3 citation statements)

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“…In contrast, 1-methoxy-3-methylimidazolium iodide (3) and 1,3-dimethoxyimidazolium hexafluorophosphate (4) gave complete conversion after two hours at 65 • C in either pyridine or methanol, yielding the thiones 12 and 13, respectively. 1,3-Dimethoxyimidazolium salts are known to undergo degradation in alkaline aqueous solution involving carbene formation and ring opening [49]. It is interesting enough that the desired thione was formed at all, but surprisingly no degradation occurred in methanol as judged by the absence of the tell-tale methyl NMR signals of the degradation product.…”

Section: Synthetic Considerationsmentioning

confidence: 99%

Synthesis and Crystal Structures of New 1,3-Disubstituted Imidazoline-2-thiones

Laus

Kahlenberg

Wurst

et al. 2013

Zeitschrift Für Naturforschung B

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Two methods (MeOH/K 2 CO 3 , pyridine/Et 3 N) were assessed for the introduction of sulfur into the 2-position of 1,3-disubstituted quaternary imidazolium salts 1-9 (Cl, I, BF 4 , PF 6 , CH 3 OSO 3 were used as anions) to yield nine 1,3-disubstituted imidazoline-2-thiones 10-18 (1, 10: R 1 = CH 3 , R 2 = CH 3 ; 2, 11: R 1 = OCH 2 Ph, R 2 = CH 3 ; 3, 12: R 1 = OCH 3 , R 2 = CH 3 ; 4, 13: R 1 = OCH 3 , R 2 = OCH 3 ; 5, 14: R 1 = NH 2 , R 2 = CH 2 Ph; 6, 15: R 1 = NCHPh, R 2 = CH 3 ; 7, 16: R 1 = NH 2 , R 2 = CH 3 ; 8, 17: R 1 = NCHPh, R 2 = NCHPh; 9, 18: R 1 = NH 2 , R 2 = OCH 3 ). Compounds 11-18 represent N-alkyloxy and N-amino imidazoline-2-thiones, whereas 10 served as reference compound. The first method was advantageous for the conversion 1 → 10 due to faster reaction, whereas in the reaction 2 → 11 considerable amounts of by-products were formed. Pure thiones 11, 14, 16, 17, and 18 were obtained only by the second method. Both methods worked for the synthesis of the methoxy derivatives 12 and 13 from 3 and 4, and the benzylideneamino derivative 15 from 6. 1-Amino-3-methylimidazoline-2-thione (16) was also prepared by hydrolysis of the benzylideneamino derivative 15. Crystal structures of seven 1,3-disubstituted imidazoline-2-thiones were determined by singlecrystal X-ray diffraction. Intermolecular C-H···S contacts were identified and, additionally, N-H···S interactions in aminothiones 14 and 16. The 1 H NMR shifts of 10 and 13 were satisfactorily correlated with the Kamlet-Abboud-Taft π * and β parameters in ten solvents. From the lack of correlation with the α parameter and from the C=S bond length (average 1.68Å) a significant contribution of a mesoionic imidazolium-2-thiolate resonance structure seems unlikely.

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Section: Synthetic Considerationsmentioning

confidence: 99%

Synthesis and Crystal Structures of New 1,3-Disubstituted Imidazoline-2-thiones

Laus

Kahlenberg

Wurst

et al. 2013

Zeitschrift Für Naturforschung B

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“…The side chain C4-C5-N3-O3-C7 adopts an almost planar conformation (deviations: C4, 0.012 Å; C5, 0.006 Å; N3, 0.018 Å; O3, 0.007 Å; C7, 0.006 Å), only the carbonyl oxygen atom O2 exhibits adistance of 0.417 Åfrom this plane. The most striking difference between the structures of the free ligand [1] and the coordinated ligand is the orientation of the side chain. In the title compound, the C4-C5 bond is rotated out of the imidazole ring plane by 50°, whereas in the free ligand it remains coplanar with the heterocyclic ring.…”

Section: Discussionmentioning

confidence: 99%

“…The nitrogen atom N3 of the side chain does not participate in any interaction which is in contrast to the situation in the free ligand [1]. Theimidazole ringsare orientedinaparallel manner,stacked in the direction of the crystallographic b axis, with an interplanar distance of 8.14 Å. Symmetry codes i: 1+x,y,z;ii: -1-x,1-y,-z.…”

Section: Discussionmentioning

confidence: 99%