Sequential One-Pot Synthesis
of Tri- and Tetrasubstituted
Thiophenes and Fluorescent Push–Pull Thiophene Acrylates Involving
(Het)aryl Dithioesters as Thiocarbonyl Precursors
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Abstract
An efficient, one-pot three component
synthesis of highly functionalized
tri- and tetrasubstituted thiophenes has been reported involving (het)aryl
dithioesters as thiocarbonyl precursors. Thus, sequential base mediated
condensation of readily available (het)aryl active methylene ketones
with (het)aryl dithioesters followed by <i>S</i>-alkylation
of the resulting enethiolate salts with activated halomethylene compounds
and concurrent intramolecular aldol-type condensation of <i>S</i>-alkylated compounds affords substituted thiophenes in excellent
yields. The methodology has also been extended for the synthesis of
highly fluorescent push–pull substituted thiophene-5-acrylates
by using bromocrotonate as the activated methylene alkylating agent