Cyclophosphazenes synthesis

The diazaphosphane or aminoiminophosphane ligands with a NPN framework are another subclass of cyclophosphazenes. These compounds with both phosphorus in oxidation state (111) [104-110] and (V) [111-112] have been employed in the synthesis of four membered heterocycles and coordination chemistry with group 13 derivatives. Several complexes of trivalent phosphorus derivatives with both aluminum halide and alkyls are known as illustrated for 48 in Scheme 21 [113-119]. The structure determination of 48 confirms the formation of a four membered metallacycle [116, 117],... 

Ph2P(NH2)NP(NH2)Ph2]+Cl, 19, which is prepared by the reaction of Ph2PCl3 and ammonia (136). This synthon has a preformed N-P-N-P-N unit and can be readily cyclized to a six or higher membered ring upon reaction with an appropriate reagent (137). An important application of the use of the Bezman s salt approach has been the synthesis of metallocyclophosphazenes of the type 20, which contain an early transition metal in the framework of the cyclophosphazene skeleton [Fig. 15(A)] (138). A modification of the Bezman s salt to design a chiral synthon allowed the synthesis of an optically pure cyclophosphazene (139). 

Scattered reports of the synthesis of the cyclophosphazene ring system from the aminolysis of halophosphoranes continue to appear. The most interesting of these is the synthesis of the first spirocyclic organophosphazenes, [(C PNlj from (C )... 

Reactions at the exocyclic position of cyclophosphazene derivatives represent a means for widely expanding the range of available phosphazenes. The synthesis of covalently bound cyclophosphazene heme complexes starts with N3P3 (OPh), -Cl which is converted to N3P3(OPh)5NMeCH2CH2CN. Following reduction of the... 

Polyphosphazenes and cyclophosphazenes are almost unique as carrier molecules for transition metals because of the wide range of binding sites that can be incorporated into the phosphazene structure. The substitutive mode of synthesis described earlier allows a structural diversity that is not found, for example, in polystyrene, polyphenylene oxide, or other organic carrier polymers. 

Ratz et al. reported on the synthesis of this cyclophosphazene in which the chlorine atoms of NjPjClg are substituted by 2- methyl aziridine (propyleneimine) groups in the presence of H3N or Et3N in benzene. However, the original paper provides only very few characteristics of the sample in question, i.e., elemental analysis and refractive index, n = 1.5071. 

The comparison of the two sets of %ILS values allows us to conclude that MYKOMET 63 appears to be actually as active as MYKO 63, but not more active. In other words, the graft of methylated aziridinyl ligands on a six-membered cyclophosphazene ring does not significantly improve the antitumoral activity with respect to the non-methylated isologues. However, because MYKOMET 63 possesses only a slight toxicity compared to MYKO 63, the new drug reported here may be of interest for eventual clinical use, no matter what difficulties are encountered in its synthesis. 

The original synthesis of these chemicals has been reported elsewhere . Their purity was checked by classical IR, and nmr as well as by HPLC and mass spectrometry . In the cyclophosphathiazenes mass spectra there are mass peaks caused by fracture of the NPS rings this was particularly noticeable with DISOF and in complete contrast to the cyclophosphazenes analogous . These observations are consistent with the proposed stability of the ring systems. 

Chloro and bromo cyclophosphazenes are generally prepared by the reaction of chloro or bromophosphoranes with ammonium halides [15] (Eq. 2 and Scheme 1). Special methods are also available for the synthesis of chlorocyclophos-phazenes (Scheme 1). In these reactions cyclic oligomers and linear products are formed, and the former compounds are easily separated from the mixture because of their greater solubility in petroleum solvents. Maximization of cyclic... 

Scheme 2.2 Synthesis of hybrid cyclophosphazenes from [Cl3P=N=PCl3] ...

Various aspects of the chemistry of cyclophosphazenes have been discussed in earlier chapters, viz. synthesis (see Scheme 2.1), electronic structure (see Section 4.1.2.2 and Figure 4.2), macrocyclic ring systems (see Section 6.2.2 and Figure 6.4) and ligand behaviour (see 7.20 and 7.21 in Section 7.1.3). Phos-phazene polymers are considered in Section 11.4.3. In this section, emphasis will be placed on new developments in cyclophosphazene chemistry that are not covered elsewhere in this book. 

The air-stable linear phosphazene (3) prepared from the reaction of Ph2PCl3 with ammonia in chloroform (57, 225) has proved a useful intermediate for cyclization reactions (Fig. 1) (379). A noteworthy feature of this approach is the synthesis of cyclophosphazenes in which hydrogen is attached to phosphorus (56, 378, 382). The only other route (383) reported for the preparation of a hydridocyclophosphazene derivative is... 

This section reports on the synthesis and characterization of the second SPIRO-ANSA structure (for the first one, see Ref. 66 ) and of the first DISPIRO-DIANSA-BINO cyclophosphazene. 

In addition to classical substituents such as NH2, NHR, NR2, OR, SR in various combinations, in recent years some more exotic groups have been attached to phosphazene rings. Among the novel cyclic phosphazenes the carbo-rane substituted derivatives are worth mentioning. Other unusual derivatives include chiral cyclophosphazenes, cyano-, ferrocenylphenoxy-, and ferrocenylhydrazone-cyclophosphazenes. Another interesting development is the synthesis of crown ethers with chlorocyclophosphazene subunits (Scheme 54). ... 

The synthesis of cyclophosphazenes bridged to exocyclic groups via oxygen atoms also continue to attract attention. 

The synthesis of new cyclophosphazene derivatives by reactions of the exocyclic groups now represents a major route to these materials. 

The ultimate objective of this investigation is the synthesis of advanced and thermally stable organically modified siloxanes by incorporation of 6-membered ring structures of triamino triazine A and cyclophosphazene B (Fig. 1.). It is therefore necessary to synthesize novel monomeric precursor compounds for sol-gel processing, which possess 6-membered ring structures chemically linked to alkoxysilyl moieties. 

Focused reviews of various aspects of cyclophosphazene chemistry including the relation of exocyclic substituents to polymerizability and synthetic transformations of organometallic and bioactive phosphazenes , a summary of variables involved in the synthesis of bicyclic phosphazenes... 

In phosphazene chemistry, preparation and reactions of small molecule, linear phosphazenes continue to attract interest. This year numerous papers have explored the utility of the aza-Wittig reaction in the synthesis of complex molecules with particular reference to nitrogen heterocycles. In cyclophosphazene chemistry, the shift of emphasis to materials which are monomers themselves or models for phosphazene polymers is apparent. The synthesis and characterization of poly(phosphazenes) is an active area with extensive interest in phosphazene based polyelectrolytes being noted. Solid state NMR has been shown to be a valuable tool for the study of both structure and phase changes in poly(phosphazenes). 

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