Hydroxylamine diphenylphosphinate

The Step 1 product (5.10 mmol) dissolved in THF cooled to — 15°C was treated dropwise with diphenylphosphinic chloride (6.63 mol), then stirred 20 minutes and further treated with Al-methyl morpholine (6.375 mmol), and stirred additional 20 minutes. (/ )-0-(2,2-dimethyl-[l,3]dioxolan 4-yl methyl )-hydroxylamine (5.1 mmol) was added and the mixture stirred for 1 hour. Additional At-methyl morpholine (6.37 mmol) was added and the mixture stirred 12 hours at ambient temperature and was then concentrated. The residue was diluted with EtOAc, washed twice with saturated NaHC03 solution, once with brine, dried using Na2S04, and reconcentrated. The residue was purified by chromatography with silica gel using hexane/EtOAc, 4 1, and the product isolated in 68% yield. 

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. ... 

In further studies relevant to the mechanism of the Mitsunobu reaction, the reaction of diphenylphosphine (40) with di-isopropyl azodicarboxylate (41) was found to give a mixture of products one of which was assigned structure (44) formed via (42) and (43). The reaction of trico-ordinate phosphorus compounds with ortho-quinones,p-ketoalkenes and p-ketoimines is also a well-established source of pentaco-ordinate phosphorus compounds but in some cases the dipolar ion structure is more stable. Thus the reaction of (4Sab) with (46) produced the dipolar ion structures (47ab) but on the other hand, reaction of (45b) with the quinone imine (48) produced what appeared to be an equilibrium mixture of (49) and the pentaco-ordinate structure (50). The 1,3,2-X o -diazaphospholenes (Slab) have proved to be useful synthetic reagents in that on hydrolysis they yield the bis-hydroxylamine (52) which reacts with benzaldehyde to form the imidazoline (53). ... 

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