Nucleophilic Halogenation of Cyclic Nitronates: A General Access to 3-Halo-1,2-Oxazines
Roman S Malykhin1,2, Aleksandr O Kokuev1,3, Valentin S Dorokhov1,3
1N. D. Zelinsky Institute of Organic Chemistry , Russian Academy of Sciences , 119991 , Leninsky prospect, 47 , Moscow , Russian Federation.
Abstract:
In this article, comprehensive studies on the nucleophilic chlorination and bromination of readily available six-membered cyclic nitronates (1,2-oxazine-N-oxides) are reported. Under optimized conditions (POCl3 or (COBr)2 with Hünig's base), 3-halo-substituted 1,2-oxazines, which are difficult to access by other routes, were obtained in good to high yields. The latter were shown to be convenient precursors to other 3-substituted 1,2-oxazine derivatives using Lewis/Brønsted acid-assisted substitution of the halide atom for C-, S-, and N-nucleophiles.
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