Phosphonic diacid

For the synthesis of simple peptides in which the phosphorus-containing amino acid analogue is at the C-terminal end of the peptide, acid-catalyzed cleavage of the diester has been used to produce the phosphonic diacid.153,6X1 However, the strong acid needed to effect this transformation makes the strategy unattractive for more complex molecules and it has largely been superceded by the use of bromotrimethylsilane (see Section 10.10.3.2.1). 

From all these results it was concluded that the polymerization was controlled and that it was possible to prepare well-defined copolymers with a phosphonated-containing polyacrylamide moiety. It is also interesting to note that homo and diblock copolymers were successfully hydrolyzed, thus producing phosphonic diacid groups, using bromotrimethylsilane and methanol. 

Fig. 3. Synthesis of diacidic and monoacidic N-1 a2etidinone phosphonates and phosphinates where TMSBr is trimethylsilyl bromide BSA is...

Phosphonic acid and its derivatives Various alcohols and diacids 40,166... 

Photosensitive functions are in many cases also heat sensitive, so the preparation of photosensitive polyimides needs smooth conditions for the condensations and imidization reactions. Some chemical reactants, which can be used for polyamide preparation, have been patented for the synthesis of polyimides and polyimide precursors. For example, chemical imidization takes place at room temperature by using phosphonic derivative of a thiabenzothiazoline.102 A mixture of N -hydroxybenzotriazole and dicyclohexylcarbodiimide allows the room temperature condensation of diacid di(photosensitive) ester with a diamine.103 Dimethyl-2-chloro-imidazolinium chloride (Fig. 5.25) has been patented for the cyclization of a maleamic acid in toluene at 90°C.104 The chemistry of imidazolide has been recently investigated for the synthesis of polyimide precursor.105 As shown in Fig. 5.26, a secondary amine reacts with a dianhydride giving meta- and para-diamide diacid. The carbonyldiimidazole... 

There have been efforts to form aromatic polyamides directly from diacids at moderate temperatures by using various phosphorus compounds for in situ activation of the carboxyl groups [Arai et al., 1985 Higashi and Kohayashi, 1989 Krigbaum et al., 1985]. A useful agent is diphenyl(2,3-dihydro-2-thioxo-3-benzoxazolyl)phosphonate, which probably activates the carboxyl group by forming a mixed carboxylic-phosphoric anhydride [Ueda, 1999 Ueda et al., 1991]. 

Diacidic phosphonates (Vla-VId), i.e., those with two protons available for substitution, had a tendency to yield significant a-mounts of bis-substituted phosphonates [(RiC0CH20)2P0(R2) ] upon reaction with IV. However, it was found that careful addition (Table I) of the a-diazoketone to the phosphonate at reaction temperature minimized the formation of this by-product moreover, the bis-substituted phosphonates could be converted to the corresponding monoacids by refluxing the former with sodium iodide in methyl ethyl ketone. In this manner higher yields of phosphonates (e.g., Vllla-VIIId) could be obtained. 

The condensation of triphenyl phosphite, benzyl carbamate and 4-pentenal gave the protected a-aminoalkyl phosphonate 313 which was oxidised with osmium tetroxide (Scheme 95). Hydrolysis furnished the diacid 314, which cyclised into phosphonate 315 in the presence of dicyclohexylcarbodiimide. Oxidation of the primary alcohol yielded carboxylic acid 316. Several conventional steps gave the protected oxaphosphane 317 as a separable mixture of stereoisomers. Both cis and trans isomers of 312 have been tested as inhibitors of P-lactamase II from B. cereus and found to be inactive, even at concentrations up to 0.5 mM. 

In recent years, phosphorus-based polymers have been widely studied as they exhibit very unusual and interesting properties/ Whereas the ester forms are the most available compounds, monoacids and diacids can be easily obtained under mild conditions with the use of bromotrimethylsilane, opening the way to a wide range of polymers showing different properties. The latter can be explained in part by the ionization potential of phosphonic acids, which is intermediate between that of sulfonic and carbojgrlic acids due to their intermediate p/fa-... 

Kaur et al. presented the inhibition of class D p-lactamases by different acyl-phosphonates (01JACS10436). These compounds were synthetized starting with ethyl o-toluate 109. Benzylic bromination with N-bromosuccinimide followed by a subsequent Arbuzov reaction with triethyl phosphite and hydrolysis under acidic conditions afforded the phosphonic acid 110. The final dehydration of diacid 110 in refluxing xylene produced the cycHc phospho-nolactone 111 (Scheme 26). 

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