Quinoxalines. XII. On the reaction of 2-(Methylsulfonyl)quinoxaline with active methylene compounds

Abstract

Examinations were made on the reaction between 2-(methylsulfonyl)quinoxaline (I) and active methylene compounds, using ethyl cyanoacetate (IIa), ethyl acetoacetate (IIb), ethyl malonate (IIc), phenylacetonitrile (IId), nitromethane (IIe), and nitroethane (IIf). The reaction was first carried out in benzene, in the presence of sodium amide, and the products obtained were IIIa from IIa, IIIc and IIIc' from IIc, and. IIId from IId. Unexpectedly, no product was obtained from te reaction with IIb, and no reaction occurred with IIe and IIf. Next, the reaction was carried out in dimethyl sulfoxide, in the presence of potassium cyanide, and IIIa was obtained from IIa, while IVb to IVf were obtained from IIb to IIf. The sequence of this reaction is considered to be as shown by the reaction formulae in the text. It is still not clear what role potassium cyanide plays in this reaction. If I and potassium cyanide are heated in dimethyl sulfoxide, CN_ acts as a nucleophilic reagent and CH3SO2- group is- substituted to form V, and a small amount of VI is obtained at the same time. The results of these reactions and the products obtained therefrom are listed in Table I to III.