Dibenzyl phosphates

Diphenyl phosphates are converted by transesterification to dibenzyl phosphates upon treatment with BnONa in THF at 25° in 83% yield. ... 

Pd-C, EtOH, NaHC03, H2." Hydrogenolysis in the presence of NH4OAC cleaves only one benzyl group of a dibenzyl phosphate. ... 

I M TFMSA in TEA, thioanisole. Dibenzyl phosphates are only partially labile to TEA alone. 

With dibenzyl phosphates or phosphonates, treatment with refluxing A-methylmorpholine results in monodebenzylation (60-100% yield). 

Quinuclidine, toluene, reflux. In dibenzyl phosphates, only one benzyl group is removed. 

The alcoholysis of the cyclic phosphate of catechol by alditols can lead, after acid hydrolysis of intermediate, cyclic phosphates, to the selective formation of phosphoric esters of the primary hydroxyl groups in the alditols. Thus, erythritol and D-mannitol afford, after chromatographic purification of the reaction products, their 1-phosphates in yields of 31 and 38%, respectively.217 The method was used to convert riboflavine into riboflavine 5 -phosphate.218 1-Deoxy-1-fluoro-L-glycerol has been converted into the 3-(dibenzyl phosphate) in 54% yield by selective reaction with dibenzyl phosphorochloridate. 219... 

Chin at al. have also demonstrated [52] notable bimetallic cooperativ-ity with the same substrate by the Cu(II) complex 34. The dimer complex is 26 times more active (at pH = 7 and T = 298 K) than the corresponding mononuclear species 35. Based on the crystal structure of the dibenzyl phosphate bridged complex, the authors have proposed double Lewis-acid activation, as in the preceding case. 

The calculation for dibenzylphosphoenolpyruvate assumes that the enol dibenzyl phosphate will have the same reactivity towards bimolecular attack by RCOOH as the dialkyl phosphate group of A.5.5. The comparison between A.5.3 and A.5.4 shows that the substitution of an alkoxy group by phenyl increases the reactivity by an order of magnitude towards COOH, and this factor allows us to put the phosphonate A.5.1 on the scale. The intrinsic reactivity of A.5.1 and A.5.2 are assumed the same b Gordon el al., 1964 Blackburn and Brown, 1969 c van Holst el al., 1974... 

Finally, bidentate bis(guanidinium) hosts like 26 reported by Anslyn et al. have recently been shown to bind phenyl phosphate anions in a bis(bidentate) fashion. Hydrogen-bonding N(H) -0 distances are in the range 2.658(7)-2.868(6) A, while solution studies in 15% HjO/DMSO give binding constants of ca. 500 M" with dibenzyl phosphate. ... 

Koga et al. complexed oxo acids like methyl phenylphosphonate with bis(resorcinol) quinoline derivative 57 [83], Anslyn and coworkers presented a more rigid polyazacleft containing hydrogen bond acceptor and donor sites in form of pyridine rings and amino groups, respectively. The formation of the 3 1 complex 58 with dibenzyl phosphate is assumed, in which the four components are spatially fixed by a net of H-bonds [84]. 

Recently Benkovic and Schrayl28b and Clark and Kirby,26c have investigated the hydrolysis of dibenzylphosphoenolpyruvic acid and mono-benzylphospho-enolpyruvic acid which proceed via stepwise loss of benzyl alcohol (90%) and the concomitant formation of minor amounts (10%) of dibenzylphosphate and monobenzylphosphate, respectively. The pH-rate profiles for release of benzyl alcohol reveal that the hydrolytically reactive species must involve a protonated carboxyl group or its kinetic equivalent. In the presence of hydroxylamine the course of the reaction for the dibenzyl ester is diverted to the formation of dibenzyl phosphate (98%) and pyruvic acid oxime hydroxamate but remains unchanged for the monobenzyl ester except for production of pyruvic acid oxime hydroxamate. The latter presumably arises from phosphoenolpyruvate hydroxamate. These facts were rationalized according to scheme (44) for the dibenzyl ester, viz. 

Figure 10. Reaction of the oxazoline 30 with dibenzyl phosphate.

Figure 4. Reactions of2-(fatty alkyl)oxazolines with dibenzyl phosphate.

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