O-Diphenylphosphinyl hydroxylamine

Die 1-Aminierung mit O-Diphenylphosphinyl-hydroxylamin und Natriumhydrid in 1-Methyl-2-oxo-pyrrolidin ist sowohl fur wasserlosliche als auch fur wasserunlosliche Imidazole geeignet. Auch hier werden die Produkte iiblicherweise iiber die 1-Benzylidenamino-imidazole ge-reinigt. Auf diese Weise werden 1-Amino-611, l-Amino-4-nitro-611, l-Amino-2-methyl-4-ni(ro-611, l-Amino-2-methyl-61s und l-Amino-2-phenyl-imidazol678 hergestellt. 

Hydroxylamines usually react with acid chlorides to give mixtures of N-, O- and poly-acylated products. In contrast reaction of tris(trimethylsilyl)hydroxylamine (65) with aliphatic acid chlorides leads selectively under /V-monoacylation to the corresponding hydroxamic acids (66 equation 26). While di-phenylphosphinic chloride (68) is attacked by the oxygen of hydroxylamine to yield 0-(diphenylphos-phinyl)hydroxylamine (67 Scheme 13), A -(diphenylphosphinyl)hydroxylamine (69) can be obtained by treatment of diphenylphosphinic chloride with 0-trimethylsilylhydroxylamine followed by removal of the silyl blocking group (Scheme 13). 0-Acylation of arylhydroxylamines can be achieved with acyl cyanides. ... 

A two-step procedure for the oxidation of amines to hydroxylamines involves nucleophilic displacement along the peroxide bond of dibenzoyl peroxide and saponification of the intermediate O-ben-zoylhydroxylamine. Primary and secondary amines have been oxidized in this way (equation 29). Related reactions for transformation of amines to O-(arylsulfonyl)- and O-phosphinyl-hydroxylamines have been described by means of bis(arylsulfonyl) and bis(diphenylphosphinyl) peroxide, respectively 86,87... 

Electrophilic N-aminations have been performed with hydroxylamine-O-sulfonic acid (HOSA)," O-(2,4-dinitrophenyl)hydroxylamine and C>-mesitylenesulfonylhydroxylamine. The use of HOSA is mainly restricted to aqueous reaction media. Imide sodium salts of some heterocycles such as theobromine (88) can be converted to hydrazine derivatives by treatment with 0-(diphenylphosphinyl)hydroxylamine (equation 35)." This reaction has been extended to synthesis of N-arylhyd ines, where R and R are hydrogen, alkyl or aryl (equation 36)." Similarly, trisubstituted hydrazines can be prepared by the use of N-aryl-O-acetylhy oxylamines and secondary amines." A recent publication" concerning the synthesis of l-acyl-2-dkylhydrazines from hydroxamic acids and amines in the presence of activating agents has been found to be erroneous no N—N bond formation occurs under these conditions." ... 

A. O-Diphenylphosphinylhydi oxylamine. A 5ilO-mL, round-bottomed flask, equipped with a reflux condenser, drying tube, an efficient mechanical stirrer, a dropping funnel and a nitrogen-inlet tube, 1s charged with 300 mL of anhydrous methylene chloride, 16.5 g (0.5 mol) of hydroxylamine base (Note 1), and 1,0 g of dry sodium bicarbonate. While the suspension 1s stirred vigorously at -30°C (bath temperature), a solution of 52.06 g (0.22 mol) of diphenylphosphinyl chloride (Note 2) in 70 mL of anhydrous methylene chloride... 

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