Brian T. Gregg, Ph.D., William G. Earley, Ph.D, Kathryn C. Golden, John F. Quinn, Ph.D, Dana A. Razzano and W. Martin Rennells
The novel Lewis acid catalyzed condensation of aldehydes with 3-alkyl-1-methyl-thioxo-imidazolidin-4-ones (thiohydantoins) to generate the corresponding (E)/(Z) 5-arylidene-3-alkyl-1-methyl-2-thioxo-imidazolidin-4-ones (arylidene thiohydantoins) is presented. A survey of various catalysts was conducted (either indium(III) triflate, aluminum trichloride, or boron trifluoride diethyl etherate) and compared with the uncatalyzed reactions.
In most examples, the Lewis acid promoted catalysis yielded reactions exhibiting increased reactivity, conversion and purity profiles as compared to the uncatalyzed reactions. Since arylidene thiohydantoins are reported in the literature as being biologically relevant moieties for antimicrobial, antiviral, immunosuppressive and potentially anticonvulsant indications, this validated protocol was then used as part of our parallel synthesis efforts to generate a library of approximately 400 target compounds.
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