Hydroxyamines rearrangement

Oxyamination.2 The reagent has been used to effect hydroxyamination of alkencs with aryl amines (equation I). The rearranged isomer 1 is the major product with terminal alkenes (R3 = R4 = H). 

The reaction of ketone 243 with hydroxyamine resulted in the formation of oxime 244. Treatment of this oxime with polyphosphoric acid induced the Beckmann rearrangement of oxime 244 to form lactam 245 without detectable formation of isomeric lactam (Scheme 43) <1997JHG921>. Other examples of the Beckmann rearrangement of pyran and thiane derivatives have been reported <2004BML5907, 2004TL1051, 2005JOC10132>. 

The reaction of methyl (3-hydroxypyridin-2-yl)ketone oxime (487) with thionyl chloride, trichloroacetyl isocyanate or chlorosulfonyl isocyanate gave 3-methylisoxazolo[4,5-6]pyridine (488) in varying yields dependent upon the temperature and solvent (Equation (43)) <87H(26)292l>. Trichloroacetyl isocyanate was particularly effective in the formation of compound (488) in either diethyl ether or tetrahydrofuran, at ambient temperature or at reflux, affording 60-78% yields. The treatment of 2-acetyl-3-hydroxypyridine (489) with hydroxyamine 0-sulfonic acid afforded a 1 1 mixture of compound (488) and 2-methyloxazolo[4,5-6]pyridine (490) (Equation (44)). The formation of the isomer (490) results from a Beckmann rearrangement. 

A wide variety of hydroxylamines, e.g. 7V-phenylhydroxylamine, 0-benzoyl-A-ter/-butylhy-droxylamine, and A-(a-cyanoalkyl)hydroxylamines, added smoothly to cyclopropanone or 1-acetoxycyclopropanol to form the adducts 13, 15 and 17, which were conveniently converted into -lactams 14, 16 and 19 a procedure which resembles the cyclopropylcarbinyl cyclobutyl rearrangement. The former two reagents gave hydroxyamine-type adducts 13 and 15, which rearranged spontaneously into )5-lactams, while with the latter reagent subsequent reaction of the adduct 17 with p-toluenesulfonyl chloride was required to form a species 18 which easily underwent ring enlargement. ... 

Use of m-chloroperbenzoic acid provides an amine oxin complete chirality transfer to a hydroxyamine (5). 6 whlch rearranges with... 

Compound 327 is identical with the product earlier prepared by pyrolytic rearrangement by the English workers (153). Hydrogenation of compounds 327 and 328 gave the same dihydro derivative. Deketalization of 328 yielded the corresponding ketone (329), which was reduced with lithium aluminum hydride to give a mixture of the epimeric hydroxyamines 330 and 331. Treatment of 330 and 331 with mercuric acetate afforded thfe epimeric products 332 and 333. Jones oxidation of this epimeric mixture yielded compound 322, whose structure was confirmed by an X-ray crystallographic analysis. 

The rearrangement of hydroxyamine derivatives has also been apphed to the synthesis of 2-substituted indoles <87T3237>. 

In other reactions that proceed via an acyliminium ion, O-vinyl iV,0-acetals rearrange smoothly to /3-(A-acylainino)aldehydes at 0 °C in CH2CI2 in the presence of TMSOTf with moderate to high diastereoselectivities (eq 78). However, TMSOTf failed to promote aprotic alk)fne-iminium cyclizations, which are readily enhanced by TMSCl, TMSBr, or SiCU. On the other hand, TMSOTf assists in the addition of enols to heteroaromatic imines or hydroxyaminal intermediates. ... 

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