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New Regiospecific Catalytic Approaches to 4,5-Dihydroisoxazoles and 2,5-Dihydroisoxazoles from O-Propargylic Hydroxylamines

David W. Knight*, Anthony J. Proctor, John M. Clough

*School of Chemistry, Cardiff University, Main College, Park Place, Cardiff, CF10 3AT, UK, Email:

D. W. Knight, A. J. Proctor, J. M. Clough, Synlett, 2010, 628-632.

DOI: 10.1055/s-0029-1219365

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Unprotected O-propargylic hydroxylamines undergo cyclisations when exposed briefly to silver nitrate adsorbed onto silica gel to give 4,5-dihydroisoxazoles [2-isoxazolines] in very good yields, while N-acetyl derivatives give the corresponding 2,5-dihydroisoxazoles [3-isoxazolines] in similar yields.

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Key Words

4,5-dihydroisoxazoles, 2,5-dihydroisoxazoles, O-propargylic hydroxylamines, cyclisations, silver nitrate on silica gel

ID: J60-Y2010-0540