Reaction of Nitromethane with Cinnamoyl Derivatives of Cyclic β-dicarbonyl Compounds. Application to the Synthesis of 2(3)-(4-aryl-pyrrolidin-2-ylidene)-1,3(2,4)-diones*
We have shown that reaction of nitromethane with cinnamoyl derivatives of five- and six-membered carbo- and heterocylic β-dicarbonyl compounds in the presence of 1,1,3,3-tetramethylguanidine proceeds according to the mechanism of 1,4-conjugate addition to the enone fragment of cinnamoyl moiety to give 2(3)-( 3-aryl-4-nitrobutanoyl)-substituted cyclic 1,3- or 2,4-diones in good to excellent yields. Chemoselective reduction of nitro function of the latter leads to synthetically useful and biologically interesting 2(3)-(4-arylpyrrolidin-2-ylidene) derivatives.