Cinnolines. V. On the reaction of 4-(methylsulfonyl)cinnoline or 4-cinnolinecarbonitrile with ketones in dimethyl sulfoxide in the presence of potassium cyanide

Abstract

The reaction of 4-(methylsulfonyl) cinnoline (I) and acetophenone (IIa) in dimethyl sulfoxide, by heating in the presence of potassium cyanide at 100° for 5 hours affords 2-(4-cinnolinyl) acetophenone (IIIa), 3-methyl-4-cinnolinecarbonitrile (IVa), and 4-cinnolinecarbonitrile (V) as crystalline products (Chart 2), but their yield is very low. The formation of IVa was assumed to be the result of the reaction of initially formed V with IIa. In fact, IVa was formed from V and IIa under the same reaction conditions. The same reaction carried out in the presence of potassium carbonate, assumed to have been present as an impurity in potassium cyanide, in place of the latter affords 4, 4'-methylene-dicinnoline (IIIa') from V and IIa and not IVa (Chart 3). Results of reaction between other ketones and I or V are listed in Tables I, II, and III. There are still many obscure points in this reaction, and examinations must still be made on the principle of the action of potassium cyanide, reaction solvents, etc.