Hydroxamic startg

A soln. of startg. hydroxamic acid in dichloromethane treated with a 20% molar excess of methyl triflate at room temp, for 48 h - intermediate nitrone hydrotriflate (Y 95%), in deuteriochloroform deprotonated with a 20% molar excess of triethylamine methyl N-(l,l-dimethylethyl)-benzenecarboximidate N-oxide (Y 85% overall). The products are relatively unstable, being converted to 1-functionalized nitrones with a variety of nucleophiles. F.e., also with ethyl triflate, and deprotonation on silica gel or with the weakly basic anion exchange resin. Bio-rad AG3-X4, s. J.A. Warshaw et al., J. Org. Chem. 54, 1736-43 (1989). 

Oxindoles. A soln. of startg. hydroxamate in methylene chloride treated with 1 eq. acetic acid and 2 eqs. anhydrous FeCl3 at room temp, for a few h - oxindole. Y 15%. F.e. incl. 3,4-dihydrocarbostyrils s. M. Cherest, X. Lusinchi, Tetrahedron Letters 30, 715-8 (1989). 

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