Highly Efficient P(III)-to-P(V) Oxidative Rearrangement

A rapid and efficient P(III)-to-P(V) intramolecular rearrangement of N-[(phosphino)oxy] amines is reported. This intermediate is generated in situ from the reaction of hydroxylamines with chlorophosphites or chlorophosphoramidites and with rearrangement via the cleavage of the weaker N─O bond to generate a more stable P═O bond. The reaction proceeds spontaneously in an excellent yield when the hydroxylamine is electron poor. Various substituents on the phosphorus are well-tolerated.

Keywords:

• Chlorophosphite
• chlorophosphoramidite
• hydroxylamine
• (phosphino)oxy amine
• rearrangement

We thank the National Sciences and Engineering Research Council of Canada for financial support. Feng Gao is grateful to the Canadian Institute of Health and Research for a scholarship. Supplementary information is available, including detailed descriptions of experimental procedures, product characterization, HPLC traces, and NMR spectra for compounds 4a, 5a–5f, and 6a.

Notes

^a all reactions were carried at room temperature for 2 h in dichloromethane and using the base diisopropylethylamine. No chromatography was required to purify except for 5f.

^b Isolated yield.

^a All reactions were carried at room temperature for 2 h in dichloromethane and using the base diisopropylethylamine except for 4a, where triethylamine was used.

^b Isolated yield.

^c by ³¹P NMR (data not shown).