Hydroxylamino oximes

Six-membered cyclic nitrones of the tetrahydropyrimidine series (165A) were obtained from the condensation of ft-hydroxylamino-oxime (164) with acetaldehyde (Scheme 2.58) (321). 

Glyoxal reacts with primary amines to give diazadienes which cyclize in the presence of dry HCl to form imidazolium salts <86CB1868>. Similar methods have b n applied to the synthesis of imidazoline and benzimidazole 1-oxides (or their tautomers). Thus, 1-hydroxylamino oximes react at room temperature with formaldehyde (or on heating with other aldehydes) to give 1-hydroxy-3-... 

The syntheses and reactions of a-hydroxylamino-oximes have been 4 68... 

L. B.Volodarsky and A.Y.Tikhonov, Synthesis and Reactions of a-Hydroxylamino-oximes, Synthesis, 1986, 704. 

The previously unknown 5,6,7,8-tetrahydroquinazoline iVA-dioxides (253 R = H or Me) have been prepared from the hydroxylamino-oximes (252), using a method that was known to work for the formation of pyrimidine dioxides (Scheme 101). °... 

When hydroxylamine is allowed to react with hydroxamoyl chlorides, attack on nitrogen occurs with formation of the hydroxylamino-oximes XXVIII (3 ). 

In catalytic hydrogenation, a compound is reduced with molecular hydrogen in the presence of a catalyst. This reaction has found appHcations in many areas of chemistry including the preparation of amines. Nitro, nitroso, hydroxylamino, azoxy, azo, and hydrazo compounds can all be reduced to amines by catalytic hydrogenation under the right conditions. Nitriles, amides, thioamides, and oximes can also be hydrogenated to give amines (1). Some examples of these reactions foUow ... 

Oxime-(9-sulfonic acid potassium salts of pyrido[3,2,l-(/]quinazolines 180 (X = H2, O) were obtained from 7-oxo derivatives 179 (X = H2, O) by reacting with hydroxylamino-O-sulfonic acid, then with K2CO3 (98EJM763). Reaction of 2,3,6,7-tetrahydro-l//,5//-pyrido[3,2,l-//]quinazo-line-l,3,7-trione with HONH2 HCI in boiling EtOH in the presence of NaOAc afforded 7-oxime derivative (01MI28). 

With D.F.P., the reaction was far more difficult and this led Wilson to combine the hydroxylamino group with a suitably placed N structure in the same molecule. Oximes will also restore activity of poisoned cholinesterase.8... 

B. Electrical Effects of Oxime, Hydroxamic Acid, Hydroxylamino... 

Values of electrical effect substituent constants for oxime and hydroxylamino groups have been reported ° their values are set forth in Tables la-c. No value for the acid group, CO(NHOH), was available. We have estimated values for it they are given in Tables la-c. Also in Tables la-c are values for some other types of substituents either for purposes of comparison or because they were used in correlations in this work. 

Isotellurazoles 4 were obtained in low yields (3-11%) by the one-pot reaction of alkynyl ketones with hydroxylamino-O-sulfonic acid and K2Te in aqueous solution containing sodium acetate (83S824 87H1587). A plausible mechanism of the reaction includes formation of the oxime derivative and subsequent nucleophilic addition of telluride anion to the triple bond followed by cyclization to 4. The reaction is accompanied by the formation of telluro bis(alkenyl ketones) 5 in yields approximately equal to those of 4. When alkynyl aldehydes are used instead of ketones, the single reaction products are the tellurobis(alkenyl nitriles) 6 (83S824). 

Reduction of a-nitro-j6-hydroxybutyric acid to D,L-threonine [65] and similar reactions [33,66] have been investigated for the preparation of amino acids. The reduction to amine passes predominantly through the hydroxylamino derivative and only to a smaller degree through the oxime. 

The free energies of activation for rotation about the=CHNMe2 bond in some pyridazinyl-substituted dimethylformamidines have been determined, and research on N-(3-pyridazinyl)formamidoxime has provided evidence that the compound exists in the oxime, not in the hydroxylamino, form. From NMR data it is concluded that pyridazinylpyrazoles have the trans-coplanar conformation 322. The NMR spectrum of N-... 

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