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Quinine was used as a 31 P NMR shift reagent for the determination of the enantiomeric excess of diethyl 1,2-dihydroxyethanephosphonates obtained either by chemical or biocatalytic synthesis. Sharpless asymmetric dihydroxylation of diethyl trans -vinylphosphonates enabled differentiation of threo and erythro isomers of 1,2-dihydroxyphosphonates, and provided standards for the determination of the absolute configuration of each of enantiomeric pair of threo isomers.

Reaction of commercially available trialkyl phosphites with N-phthalylamino acids gave mixtures of seven products, whereas the same reaction carried out with pure triethyl phosphite yielded only the desired 2-(N-phthalytamino)-1-oxoalkanephosphonates. These compounds underwent rearrangement to the same types of products that were obtained with the commercial phosphites. This latter series of reactions was promoted by the presence of dialkyl phosphites.

Reaction of N-blocked amino acid chlorides with trialkyl phosphites is a first step in the synthesis of 2-amino-l-hydroxyalkylphosphonates. Quite surprisingly a very purl trialkyl phosphite is required m order to obtain the desired N-blocked 2-amino-1-oxoalkylphosphonate. Thus, the use of commercially rvailrble phosphites prolongation of the reaction time, or attempts for chromatographic purification of the formed oxophosphonate resulted m quite complicated mixture of products. We haw found that these products arise as a consequence of rearrangements of 1oxo-2. phtalylnmmoalLylphosphonates in a series of reactions which are promoted by that presence of dialkyl phosphite (standard impurity present m commercially availablt trialkyl phosphites) in the reaction medium.