- A divergent and selective synthesis of isomeric benzoxazoles from a single N-Cl imine
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A divergent and regioselective synthesis of either 3-substituted benzisoxazoles or 2-substituted benzoxazoles from readily accessible ortho-hydroxyaryl N-H ketimines is described. The reaction proceeds in two distinct pathways through a common N-Cl imine intermediate: (a) N-O bond formation to form benzisoxazole under anhydrous conditions and (b) NaOCl mediated Beckmann-type rearrangement to form benzoxazole, respectively. The reaction path also depends on the electronic nature of the aromatic ring, with the electron-rich aromatic rings favoring the rearrangement and the electron-deficient rings favoring the N-O bond formation. A Beckmann-type rearrangement mechanism via net [1,2]-aryl migration for the formation of 2-substituted benzoxazole is proposed.
- Chen, Cheng-Yi,Andreani, Teresa,Li, Hongmei
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p. 6300 - 6303
(2012/01/05)
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- Reactivity of 1,2-Benzisoxazole 2-Oxides
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Nitration, bromination, and reaction with acetic anhydride, with halogen acids, and with sodium alkoxide, have been explored in the 1,2-benzisoxazole 2-oxide series.The nitration proceeded by simple substitution; the other reactions took place with rupture of the heterocyclic ring.Deoxygenation to the 1,2-benzisoxazoles could be accomplished, under forcing conditions.
- Boulton, A. J.,Tsoungas, Petros G.,Tsiamis, Chris
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p. 695 - 698
(2007/10/02)
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