Phosphonate dibenzyl esters

The addition of a nitroalkane to an alkenylphosphonic diester is exemplified by the interaction of nitromethane with diethyl ethenylphosphonate in the presence of NaOEt, when the product is diethyl (3-nitropropyl)phosphonate and by a similar addition to 1,1-bis(diethoxyphosphinoyl)ethane . In the initial stages of a synthesis of (4,5,6-trihydroxy-3-oxohexyl)phosphonic acid, the nitro sugar 76 was made to add to dibenzyl ethenylphosphonate, but the resultant (3-nitropropyl)phosphonic dibenzyl ester 77 was then used without isolation. ... 

The full paper has appeared on the solvolysis of the dibenzyl ester (28) of phosphoenolpyruvic acid and on the related phosphonate ester (29). Reversible phosphoryl migration from the enol oxygen to the carboxy-group occurs readily in (28) and (29) but only to a small extent - and probably not reversibly-in the monoanion (30) and phosphoenolpyruvic acid itself. These observations are readily accounted for in terms of the expected ease of pseudorotation between the various configurations of the... 

In the synthesis of 6 -deoxyhomonucleoside-6 -phosphonic acids the phosphonate was masked as the diphenyl ester [42]. On transesterification with sodium benzyloxide in dimethyl sulphoxide the dibenzyl ester was formed, and subsequently hydrogenated to give the desired compound (Fig. 6.19). 

Many communications have concentrated on specific amino phosphonic acids or derivative types. Thus, esters of phosphonoaminoacetic add were obtained by the reactions between trialkyl (ethyl) phosphite and (218) and which are thought to proceed via the phosphorane (219). A sequence has been presented for the preparation of the mono- and di-benzyl esters of N-chz protected (a-aminoben-zyl)phosphonic acid. A synthesis of (aminomethylene)bisphosphonic acid from dibenzylamine, dibenzyl hydrogenphosphonate and triethyl orthoformate has been noted and the asymmetric hydrogenation of (220) in the presence of chiral phosphine catalysts yields samples of (221) with e.e.s of 63-96%. The pyrrolidine-based compound (222) has been prepared from methyl S)-N-methoxycarbonyl-4-oxo-2-pyrrolidinecarboxylate and iV-coupled 4-amino-butanal diethyl acetals were the starting materials in syntheses of the pyrrolidine-2-phosphonic add derivatives (223) in which Z represents the iV-protected amino add or peptide moiety. ... 

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