Synthesis of N-aryl-5-alkylidene-2,5-dihydropyrrol-2-ones by "cyclization/Dimroth rearrangement" reactions of 1,3-dicarbonyl dianions with diimidoyl dichlorides of oxalic acid

The reaction of dilithiated dicarbonyl compounds with oxal-diimidoyl dichlorides resulted in regio- and (E)/(Z)-diastereo-selective formation of 5-alkylidene-3-arylamino-2,5-dihydropyrrol-2 -ones. The products were formed by a domino "cyclization/Dimroth rearrangement" reaction. The mechanism and preparative scope of the cyclization was studied. The arylamino groups of the products were removed chemoselec-tively under mild conditions and in high yields by hydrolytic cleavage. The products, N-aryl-5-alkylidene-3-hydroxy-2,5dihydropyrrol-2-ories, are of considerable interest from pharmacological and synthetic viewpoints. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).