Hydroxylamine reaction with isocyanate

Formal substitution of the carbonyl group of enaminones by an imino group leads to enamino imines. In the reaction with isocyanates or isothiocyanates they result in urea or thiourea derivatives, which can be transformed to pyrimidines or pyrimidones depending on substitution340 (equation 258). Treatment of similar enaminoimines with hydroxylamine gives regiospecifically isoxazoles by thermal cyclocondensation of the isolated oximes341 (equation 259). 

Tris(TMS)phosphine can undergo a related reaction with isocyanates to furnish carbamoylphosphines and their imidate tautomers in a ratio of 9 1. Such compounds are used in the synthesis of 1,2,4-azadiphospholes and 1,3-azaphos-phinines (eq 11). Reaction with imidoyl chlorides can give 2-phosphaallylic cations,which can be condensed with hydroxylamine to give 1,2,4-oxazaphospholes and 1,2,4-diazaphospholes. " Selected examples are given in eq 12. 

The synthesis consists in forming the oxime by reaction of a carbonyl compound ( aldehyde or ketone ) with hydroxylamine followed by reaction with an isocyanate... 

Oximes react with isocyanates according to R—NOH + OCNR —y R=NOCONHR. In the case of hydroxylamine, the reaction takes place preferentially with the amino group and then with the hydroxyl group. Campbell (65) used the reaction between diisocyanates and dioximes for the preparation of polymers. Of the three catalysts tried, triethylamine proved to be generally applicable and the most effective one. 

Methazole (32) is prepared from N-(3,4-dichlorophenyl)hydroxylamine in two steps. In the first step, reaction with methyl isocyanate gives 3-(3,4-dichlorophenyl)- -hydroxy-1-methylurea, which is cyclised by reaction with a haloformate to give methazole ... 

COPPER SULFATE PENTAHYDRATE (7758-98-7) Violent reaction with strong bases, hydroxylamine, magnesium. Contact with potassium chlorate is potentially explosive. Incompatible with acetylene. Aqueous solution is an acid incompatible with sulfuric acid, caustics, ammonia, aliphatic amines, alkanolamines, amides, alkylene oxides, epichlorohydrin, organic anhydrides, isocyanates, vinyl acetate. 

Nucleophilic Reactions. M,C)-Bis(trimethylsilyl)hydroxyl-amine is a protected, lipophilic form of hydroxylamine. It reacts with a variety of electrophiles predominantly by attack on the nitrogen nucleophilic center. Reaction with acid chlorides (1 equiv) in the presence of triethylamine gives M<9-bis(trimethylsilyl)-hydroxamic acids by iV-acylation. A related reagent, tris(tri-methylsilyl)hydroxylamine, gives the same product in high yields, also by iV-acylation. Hydrolysis gives the free hydroxamic acids, whereas thermal fragmentation affords isocyanates (eq 1). ... 

The first reported synthesis of hydroxyurea (24) consists of the condensation of hy-droxylamine with potassium cyanate (Scheme 7.14) [87]. Condensation of hydroxy-lamine with ethyl carbamate also gives pure hydroxyurea in good yield after recrystallization (Scheme 7.14) [88]. Nitrogen-15 labeled hydroxyurea provides a useful tool for studying the NO-producing reactions of hydroxyurea and can be prepared by the condensation of N-15 labeled hydroxylamine with either potassium cyanate or trimethylsilyl isocyanate followed by silyl group removal (Scheme 7.14) [89, 90]. Addition of hydroxylamine to alkyl or aryl isocyanates yields alkyl or aryl N-hydroxyureas (Scheme 7.14) [91, 92]. The condensation of amines with aromatic N-hydroxy carbamates also produces N-substituted N-hydroxyureas (Scheme 7.14) [93]. 

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