Cyclizations of N-alkyl-substituted azinium cations with bifunctional nucleophiles. 28. Orientation of the nucleophile in the reaction of quinoxalinium salts with indan-1,3-dione

In reactions with quinoxalinium salts in alcoholic-base media indan-1,3-dione acts as a C nucleophile, adding at the 2 or 3 position of the heterocycle to give the corresponding ylidene derivatives; attack by the nucleophile at the C₍₃₎ atom (the position relative to the quaternary nitrogen atom) is preceded by addition of alcohol at the a position. Dissociative substitution at the C₍₂₎ atom in 2-alkoxy-3-(1,3-dioxoindan-2-ylidene)-1,2,3,4-tetrahydroquinoxalines by another nucleophile makes it possible to regard lyate complexes as probable intermediates in cyclizations of 1,4-diazinium salts with dinucleophiles.See [1] for Communication 27.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 667–674, May, 1990.