Reactions of the sodium salts of tosylhydrazones of several heteroaromatic aldehydes with an equimolar amount of acrylonitrile afforded the corresponding cyclopropane derivatives as the major products accompanied by small amounts of pyrazole derivatives. On the other hand, reactions using ten-molar equivalents of acrylonitrile gave pyrazole derivatives as major products.
A silver-catalyzed synthesis of 5-aryl-3-trifluoromethyl pyrazoles from reaction of various N'-benzylidene tolylsulfonohydrazides with ethyl 4,4,4-trifluoro-3-oxobutanoate is described. The reaction proceeds via sequential nucleophilic addition, intramolecular cyclization, elimination, and [1], [5]-H shift steps to afford the trifluoromethylated pyrazole products in moderate to excellent yields. The
On the Multiplicity of Carbenes Conjugated with Pyrrole and Furan Moieties: Molecular Orbital Calculation and Reaction of 2-(1-Methyl)pyrrolylmethylene and 2-Furylmethylene with cis- and trans-Stilbenes