Phosphorus-Nitrogen Bonded Compounds

Chiral phosphorus-nitrogen compounds, especially 264 ° and analogues, have been used extensively in asymmetric synthesis and examples are given elsewhere in this chapter. The chiral catalyst 265, combining a phosphinamide and a dioxaborolidine, has been prepared and used in the asymmetric reduction of ketones to give e.e.s up to 59%.  

---

Phosphorus-Nitrogen Bonded Compounds. - Routes to thiophosphinoyl guanidines have been explored further,and additional compounds with P-N bonds have been obtained from the corresponding phosphorus(III) com-pounds sometimes being separable into diastereoisomeric forms. ... 

Suitable methods for linking a phosphorus—nitrogen bond to the aziridine ring are the aminolysis of halogenated phosphorus compounds (2,280—282), the transamination of phosphoramines with excess aziridine (283), the reaction with phosphites (284) and phosphoramidites (285) which have a free OH group, or the reaction of phosphines with aziridines and carbon tetrachloride (286). 

A number of compounds having phosphorus-nitrogen bonds have been... 

The only known iodofluorophosphine, difluoroiodophosphine, PF2I, first synthesized in 1966 by Rudolph, Morse, and Parry (277), plays a key role for the introduction of the PF2 group into other compounds. It can be readily obtained (in 94% yield) via hydrogen iodide cleavage of the phosphorus-nitrogen bond of dimethylaminodifluorophosphine (47, 213, 277) (Section V). 

Two interesting examples of phosphorus-nitrogen bond cleavage have been reported by Cavell et al. (48), (50b) who found that dimethyla-minodifluorophosphine reacts with difluorophosphoric acid or difluoro-phosphorothioic acid F2P(X)XH (X = 0 or S) to give compounds of empirical formula [F2PX]2, which contain phosphorus in both tervalent and pentavalent oxidation states, e.g. (see also Section VII, E),... 

The compound (XCI) is naturally, as in an acid chloride, sensitive to hydrolysis. With water it yields amidosulfonic acid and phosphoric acid quantitatively the high stability of the nitrogen-sulfur bond, which is manifestly greater than that of the phosphorus-nitrogen bond, is clear from these results. 

A phosphorus-nitrogen S5mergism is seen in the flame retardant action. Therefore, flame retardant compounds containing phosphorus-nitrogen bonds have been developed. Examples are shown in Table 7.5. 

In addition to oxygen, the phosphorus can be tied to the backbone through nitrogen. Indeed, this was one of the earliest variations of the DIOP family (see Section 23.3) with PNNP (45) [22, 280, 287]. Care must be taken to avoid hydrolysis of the labile P-N bonds [22, 288]. Other examples of nitrogen-linked compounds are BDPAB (46 and 47) and its derivatives (Fig. 23.4). These ligands are clearly variations of the BINAP series [289-291]. 

---