76853-85-5Relevant academic research and scientific papers
Composes sulfures heterocycliques. LXXXVIII. Bromures et iodures de -2 thiopyrylium
Sauve, Jean-Pierre
, p. 434 - 440 (2007/10/02)
In boiling acetic acid, 2-acylmethylthio-thiopyrylium bromides 1 yield 2-(thiopyran-2-ylidenemethyl)thiopyrylium bromides 2.Best results are obtained with derivatives of acetone (R=CH3). In strong acidic medium, compounds 2 are protonated and the resulting species exists in two conformations when the thiopyran rings are substituted in the 3-position, as shown by NMR spectra in deuteriotrifluoracetic acid.The α-thiopyranylidene-ketone derived from 1 seems to be an intermediate in the mechanism which leads to the (thiopyranylidenemethyl)thiopyrylium bromide 2. Another way to this type of molecules is the action of a 2-methyl-thiopyrylium iodide on malonic acid.The compound 2 is, in this case, obtained as an iodide.A similar reaction has been observed in the 1,2-dithiole series.In the basic medium used for its preparation, the 1,2-dithiole compound rearranges whereas the 2-thiopyran compound 2 is stable and remains unchanged.
