Beilstein J. Org. Chem.2015,11, 1917–1921, doi:10.3762/bjoc.11.207
-yl)-1,3-dithiol-2-thione in the presence of trimethylphosphite. The 1,3-dithiol-2-thione derivative was in turn synthesized by the regioselective bromination of 4-acetyl[2.2]paracyclophane, then through the corresponding dithiocarbamates and 1,3-dithioliumsalts.
Keywords: dithiocarbamates; 1,3
field (ca. 180 ppm) which corresponds to the electron-deficient C-2 atom.
1,3-Dithioliumsalts are valuable precursors for tetrathiafulvalenes. There are two main synthetic approaches that are mainly based on the exploitation of the electron-deficient character of the C-2 carbon atom. One of these
involves the conversion of 2-N,N-dialkylamino-1,3-dithioliumsalts into the corresponding 2-unsubstituted 1,3-dithioliumsalts, followed by the homocoupling of the carbene intermediate that is generated under basic conditions. Unfortunately, our attempts to synthesize the 2-unsubstituted derivative from
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Graphical Abstract
Scheme 1:
Synthesis of 2-N,N-dialkylamino-4-([2.2]paracyclophan-4-yl)-1,3-dithiol-2-ylium perchlorates 5.
Beilstein J. Org. Chem.2012,8, 1999–2003, doi:10.3762/bjoc.8.226
survey revealed that a P2O5/CH3SO3H (1:10, m/v) mixture may be the cyclization agent of choice to obtain 1,3-dithioliumsalts 7g and 7h as pure compounds and in high yields [28][29]. Thus, a suspension of 6g or 6h in three parts of the ‘‘superacid’’ mixture was stirred at room temperature for 30 min to