The scandium triflate-catalyzed cycloaddition reaction
of polycyclic 1,2-dithiolethiones to maleimides is described. The
reaction constitutes an easy approach to linear as well as branched
oligomeric cis-fused dihydro[1,3]dithiolo[4,5-c]pyrrole-4,6-dione
rings interconnected by 3,5-diylidenethiomorpholine-2,6-dithione or
ylidene-6-thioxo[1,2]dithiolo[3,4-b][1,4]thiazin-3-one groups. The
presence of highly colored, highly polarized push−pull α,β-
unsaturated thione groups in their structures make these compounds
sensitive to the presence of mercury(II) cation in organic or mixed
organic/aqueous solvents.
