Simple Phosphite Hydrolysis

Triethyl phosphite does not react with aldimines in EtOH. However, the addition of HCOgH (1 eq) to the (EtO)3P/aldimine mixture in EtOH induces an exothermic reaction resulting in the exclusive formation of the iminoalkylphosphonate. Undoubtedly, the 1,4-addition of triethyl phosphite is promoted by initial protonation at the nitrogen atom, which activates the double bond toward Michael addition and generates the formate anion for the dealkylation step (Michaelis-Arbuzov reaction). The dialkyl-substituted formylphosphonates are obtained by hydrolysis of the imine function with an appropriate hydrolytic procedure using either 6 M HCl or 1 M oxalic acid. The method provides a simple and convenient access to a broad range of substituted diethyl 2-formyl-alkylphosphonates in satisfactory overall yields (45-80%). ... 

Recently, it has been shown that nucleophilic addition of neat dimethyl trimethylsilyl phosphite to serine-derived P-lactonc at I ()() C for 24 h leads specifically to the carboxylic trimethylsilyl ester by preferential transfer of the trimethylsilyl group. A simple aqueous workup induces hydrolysis of the silyl ester to give the N- and P-protected free carboxylic acid ready for activation and coupling. 

Attack on Saturated Carbon. - Ethylene dicarboxylic diphosphonic acid (EDCP, 2) has been prepared in 70% yield from 2,3-dichlorosuccinic anhydride (3) and trimethyl phosphite, followed by hydrolysis of the Arbuzov product. Tris(trimethylsilyl) phosphite, in contrast to trialkyl phosphites, attacks an oxirane carbon of epibalohydrins (4) to give the phosphonates (5). Bis(trimethylsilyl) phosphonite (6) has previously been prepared in situ and used to obtain y-ketophosphinic acids similar reactions with simple alkyl halides to give alkylphosphinic and dialkylphosphinic acids acids in high yields have now been described. ... 

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