A convenient synthesis of some arylated phenylsulfonylacetonitriles and ethyl cyanoacetates using organo-iron complexes

A general method for the synthesis of some arylated phenylsulphonylacetonitriles 6a–g, 10a, b and 16 and ethyl cyanoacetates 7a-d and 11a, b is described. Nucleophilic substitution of the cyclopentadienyliron complexes of chloroarenes 1a–g with phenylsulphonylacetonitrile 2 or ethyl cyanoacetate 3 in the presence of potassium carbonate in DMF, at room temperature under a nitrogen atmosphere gave cyclopentadienyliron complexes of arylated phenylsulphonylacetonitriles 4a–g, 8a, b and 15 and ethyl cyanoacetates 5a–d and 9a, b in very good yields (71–94%). Photolysis of these complexes liberated the arenes (70–91%). To demonstrate the versatility of this methodological approach, reactions of both carbon nucleophiles 2, 3 with dimethyl chlorobenzene complexes 1h, j gave the desired products 8a, 9a, 12 and 13 without significant steric effect. This synthesis is advantageous over all those previously reported and should be a practical route to a variety of alkanoic acid and heterocyclic precursors.