[72804-96-7]  · C12H12NO2P  · O-(Diphenylphosphinyl)hydroxylamine  · (MW 233.22)

(reagent for electrophilic aminations; H2N transfers to nucleophiles)

Physical Data: mp 133-134 °C.1

Solubility: very low in aprotic organic solvents.

Analysis of Reagent Purity: IR (cm-1): 3270, 3170, 1210.3

Preparative Methods: 1-7 Triethylamine (12.4 g, 120 mmol) in methylene chloride (20 mL) is added with stirring to a mixture of Hydroxylamine hydrochloride (3.82 g, 55.0 mmol) in methylene chloride (100 mL) at -20 °C. After stirring at -20 °C for 1.5 h, Diphenylphosphinic Chloride (11.6 g, 49.0 mmol) in methylene chloride (20 mL) is added with stirring and cooling to maintain the temperature at -20 °C. The solution is stirred for another 1.5 h. During this time the reaction mixture attains 25 °C and a precipitate is formed, composed of triethylamine hydrochloride and O-(diphenylphosphinyl)hydroxylamine (1). To this mixture, water (100 mL) is added to dissolve the triethylamine hydrochloride salts, and the remaining (1) is filtered. This product is washed with anhydrous ether, and dried over phosphorus pentoxide at 25 °C/10 mmHg overnight to yield 6.81 g (60%) (1).

Handling, Storage, and Precautions: in contrast to O-(mesitylsulfonyl)hydroxylamine, an explosion with (1) has never been observed. (1) decomposes if heated above the melting point (~140 °C). It is stable for a year if stored below 0 °C.3

Reactions with the NH group of Imidazoles and Xanthines.

The N-amination of the imidazole and xanthine NH groups in (2) and isolation of the products (3) is achieved via deprotonation, amination, and imine crystallization (eqs 1-3). The amination occurs at the N-1(7) (R3) position of the imidazole ring if this position is unsubstituted (examples a-d), and at the N-1 position of the pyrimidine ring in xanthines if the N-7 position is substituted (example e).

The yields of (3) are usually better than 70%.2,7 In a similar fashion, indole and carbazole have been N-aminated to give (4) and (5) in 52-62% yields.2,7

The N-amination of pyridine (and related compounds), although possible,2,7 is more successful with O-(Mesitylsulfonyl)hydroxylamine. Amination of a tertiary amine has been also reported.8 Aminations at phosphorus and sulfur have been observed, (one example in each case);4 again, O-(mesitylsulfonyl)hydroxylamine is the reagent of choice.

Reactions with Carbanions.

(1) aminates many types of carbanions RM to give primary amines, although the yields are low to moderate.1,5,6,9,10 With O-(mesitylsulfonyl)hydroxylamine, only more stabilized carbanions are aminated; in this case, deprotonation of the aminating reagent is more likely to occur. The amines (6)-(9) are some examples of primary amines prepared using (1).6

If the alkynylcuprate (10) is aminated with (1), the nitrile (12) is formed via the unstable primary ynamine (11) (eq 4).6

Carbanions RM can also be aminated with (13)10,11 and (14),12 which receive their high electrophilicity only after lithiation. (13) and, especially, (14) are less prone to deprotonation by RM than are (1) and, especially, O-(mesitylsulfonyl)hydroxylamine. There is an excellent review on the amination of carbanions.10

1. Sosnovsky, G.; Purgstaller, K. ZN(B) 1989, 44, 582.
2. Klötzer, W.; Stadlwieser, J.; Raneburger, J. OS 1986, 64, 96.
3. (a) Harger, M. J. P. CC 1979, 768; (b) The earlier prepared compound was thought to be N-(diphenylphosphinyl)hydroxylamine: Kreutzkamp, N.; Schindler, H. AP 1960, 293, 296.
4. Harger, M. J. P. JCS(P1) 1981, 3284.
5. Colvin, E. W.; Kirby, G. W.; Wilson, A. C. TL 1982, 23, 3835.
6. Boche, G.; Bernheim, M.; Schrott, W. TL 1982, 23, 5399.
7. Klötzer, W.; Baldinger, H.; Karpitschka, E. M.; Knoflach, J. S 1982, 592.
8. Schmidhammer, H; Obendorf, D.; Pirkner, G.-F.; Sams, T. JOC 1991, 56, 3457.
9. Kendrick, D. A.; Kolb, M. JFC 1989, 45, 265.
10. Erdik, E.; Ay, M. CRV 1989, 89, 1947.
11. Beak, P.; Basha, A.; Kokko, B.; Loo, D. JACS 1986, 108, 6016, and earlier papers cited.
12. Genet, J. P., Mallart, S.; Greck, C.; Piveteau, E. TL 1991, 32, 2359.

Gernot Boche

Philipps-Universität Marburg, Germany

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