Azides of Phosphorus

These compounds, obtainable from the respective chlorides and lithium or sodium azides, have covalent phosphorus-to-nitrogen bonds. Properties are summarized in Table XV. Triphosphonitrilic hexaazide is a colorless, explosive oil 

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Once the methods for electrophilic azidation of phosphorus-stabilized carbanions were established a variety of chiral auxiliaries were surveyed to obtain nonraccmic a-aminophosphonic acids. All the compounds tested with the exception of 9 were used in optically active form. (The precursor of 9 was more readily available in racemic form.) The results of electrophilic azidation of these substrates are summarized in Tablet, together with those of ( )-l. Where possible, both methods A and B were tested. 

In summary, although the azidation of phosphorus-stabilized carbanions at the present time is not yet as stereoselective as azidation, especially of chiral imide enolates (see Section 7.1.1.), the Evans reagents2 also provide a promising methodology for the preparation of optically active a-aminophosphonic acids12. 

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