Reactions of Chlorocyclophosphazenes with Difunctional Reagents

So far we have seen the reactions of chlorocyclophosphazenes with reagents that may be termed monofunctional. For example, a phenol in its reactions with chlorocyclophosphazenes will react as a nucleophile and form N3P3(OPh)6 containing P-0 linkages. If instead of a phenol we used a biphenol we will have two sites that can react with the phosphorus centers. In this manner there are several difunctional reagents such as diamines (ethylenediamine, 1,3-diaminopropane, phenylenediamine), diols (ethyleneglycol, 1,3-propanediol, catechol), and amino alcohols (ethanolamine, propanolamine, o-aminophenol) [2,15]. 

Jnsa products are known, although less common than spirocyclic products. Some of these require indirect synthetic procedures. For example, the reaction of N3P3(CHj)Cl5 with 1-aminopropanol affords a product N3P3(CH3)(NH(CH2)30H)CLi where the hydroxyl end of the difunctional reagent is free. The latter can be induced to react with the chlorine of the adjacent phosphorus to afford an ansa product (see Eq. 3.22). 

Another way of generating an ansa product is to prepare a cyclophos-phazene precursor that has two non-geminal chlorines in a cis orientation. Such a compound upon reaction with difunctional reagents can lead to ansa produets. Thus, the reaction of oM-ge n-cw-N3P3Cl2(OCH2CF3)4 with the sodium salt of naphthalene diol affords the ansa product (see Eq. 3.23). 

With some diols, ansa products are formed in reasonable yields, but have to be separated from the other products formed in the mixture. In this manner, for example, an interesting P-N-P crown-ether can be prepared in the reaction of N3P3CI6 with the disodium salt of an etheroxydiol (see Eq. 3.24). The structural similarity (as well as the difference) between the P-N-P crown-ether and conventional crown-ethers such as 18-crown-6-ether may be noticed [2]. 

Intermolecular-bridged products are even rare and have only been reported to be formed in the reactions of long-chain aliphatic diamines with N3P3CI6. 

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The reactions of chlorocyclophosphazenes with difunctional reagents such as diamines, diols, or amino alcohols can in principle lead to the formation of several products. These are shown in Fig. 19. The reactions of these reagents with the chlorocyclophosphazenes are discussed below. 

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