Phosphoramidates esters

Chloro- and A TV-dichloro-phosphoramidate esters (20) and (21) are readily prepared from the parent phosphoramidate by direct chlorination in mildly acidic solution but when R = Ph, the use of t-butyl hypochlorite is preferable, to avoid chlorination of the aromatic nucleus. These compounds behave as pseudohalogens, (21) reacting with olefinic compounds such as styrene to give (22), which is also formed by chlorination of the N-phosphorylaziridine (23). ... 

Aziridines are obtained in one step from oxiranes with iminophosphoranes (76CB814) or phosphoramidate esters (76TL4003). 

Preparative studies have been reported on the phosphorylation of a series of hydrazines and hydrazones and on the phosphorylation of vicinal diamines with diphenyl phosphorochloridate. The cyclic phosphoramidate esters (12) and (13) may be obtained by treatment of the appropriate acyclic... 

The bis-4-nitrophenylphosphate analogue [(NH3)5lrBNPP] reacts in a similar manner (79). The same rate law obtains and the rate constants are, ki = 4.8 X 10" L mol s and 2 = 1-2 x 10" L -mol" s at 25 °C. Despite the increased rate of production of the chelate phosphoramidate ester, it was still not observed by P NMR. Again, two products were observed by P NMR in constant ratio, independent of hydroxide concentration. They were the [(NH3)5lrNPP] ion and the complex 12, which reacted further by attack of the cis coordinated hydroxide ion on the phosphate ester. The [(NH3)5lrNPP]+ ion does not react further in the time scale of this experiment. This finding is in accord with our observations on the relative reactivity of the Co(III) and Ir(lII) complexes, which lead us to predict a half-life for hydrolysis of the [(NH3)5lrNPP] ion in IM NaOH at 25 °C of -200 h. 

The rate constant for attack of OH" on the chelated phosphoramidate ester must be at least of the order of 2 x 10 L-mol s at 25 °C, which is the rate constant for its production in lAf NaOH solution. This value represents an enormous rate enhancement for attack of OH" on the P center of free 4-nitrophenylphosphoramidate due largely to relief of strain engendered by the chelation of the ester. Similarly, the rate constant for attack of OH" on the chelate ethylphosphoramidate must be at least 5 x 10" L-mol" s" in order for the chelate not be observed in that system. 

Thus all attempts to observe the exocyclic cleavage of the ester group have thus far been thwarted by the more rapid ring-opening reaction for phosphoramidate esters. 

There are other reactions which lead from prop-2-ynyl compounds to allenic phospho-nic acid derivatives. The alkylation of diethyl hydrogenphosphonate with 3-bromopropy-ne under phase transfer conditions yields a mixture of diethylpropadienyl- and (prop-l-ynyl)-phosphonates in 85 15 ratio " The action of heat on a mixture of prop-2-ynol and a phosphoramidous ester, (RO)2PNR 2, results in elimination of R 2NH followed by its re-addition to the rearranged residue to afford a dialkyl (2-amino-prop-1-enyl)-phosphonate. ... 

Dimethyl [a-(hydroxyimino)benzyl]phosphonate is stable in mineral acid but decomposes in formic acid containing formate with the liberation of benzonitrile, but otherwise the behaviour is different from that in boiling acetic acid when an additional product, a phosphoramidate ester, is obtained by a Beckmann rearrangement. For the oximes of the (4-methoxybenzoyl)- or (4-chlorobenzoyl)-phosphonic esters, only the phosphoramidate diester 127 is obtained, but for all the substrates examined [additionally the unsubstituted benzoyl- as well as the (4-methylbenzoyl)phosphonic derivatives], the formation of the phosphoramidate ester demonstrates a high migratory aptitude of the phosphinoyl group (Scheme 22) ... 

The quinazoline-2,4-dione 117 substituted at position 3 is formed as a result of the reaction of the anhydride 1 with phosphoramidic esters 118 with heat in the presence of sodium hydride [47]... 

Finally, a bidentate ligand has also been employed to prepare cyclic phosphoramidate esters such as the cyclic compounds 67 [145]. The (N-3-hydroxypropyl)-amino esters could be prepared from commercially available amino acids, ultimately allowing preparation of both the Sp and Rp isomers, and the phosphoms stereochemistry was assigned based on NMR data. Small differences in activity were found between the phosphorus stereoisomers, and the most... 

In contrast to (7.9) and (7.10), phosphonous diamides of the type RP(NHR)NRj or RP(NHR)2 and phosphonamidous esters of the type RP(NHR)(OR) appear to remain in trivalent pyramidal form (7.11), but the already tetrahedral phosphoramidic esters of the type (RO)2P(0)NHR usually exist in the amido rather than the imidol form (7.12). 

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