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Yusuf Ahmad, M S Habib, M Iqbal, M I Qureshi, Ziauddin, Quinoxaline Derivatives. VII. The Mechanism of the Formation of 6-Chloro-1,2,3,4,2′,3′-hexahydro-4,1′-dimethyl-3,2′-dioxoquinoxaline-2-spiro-3′-indole from a Quinoxaline N-Oxide Derivative by Nucleophilic Chlorination, Bulletin of the Chemical Society of Japan, Volume 38, Issue 10, October 1965, Pages 1659–1663, https://doi.org/10.1246/bcsj.38.1659
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Abstract
The compound IVb named in the title has been obtained by an unambiguous route. It has been shown to be identical with the product of the reaction of the N-oxide (Ia) with ethanolic hydrogen chloride. Clark-Lewis and Katekar’s mechanism for the nucleophilic chlorination in the latter case has been discussed, and a modified mechanism proposed.
Isomeric 7-chloro-spiro-indole (IVc) has also been obtained by the rearrangement of the anilide IIIc. Similarly, the anilide IXi gives spiro-indole (IVc; H for Me’).
The anilides IIIb and IIIc give normal N-oxides Ib and Ic, which, with concentrated sulphuric acid, decompose and afford the amines IIb and IIc. IXi, instead of giving its N-oxide, yields 6-chloro-2,3-dihydroxyquinoxaline.