1. Field of the Invention
In many areas of chemistry, it is desirable to find simple synthetic procedures for preparing compounds. In most situations where stereoisomers are involved, any procedure should provide for the preparation of the particular desired isomer with minimal contamination of the undesired stereoisomer. The synthetic procedure is frequently only difficultly realized where the compound of interest is highly functionalized.
D,L-2-Amino-2-deoxyerythritol ("2-aminoerythritol") is of interest in the preparation of X-ray contrast media. See, for example, co-pending application Ser. No. 141,097, filed Apr. 17, 1980, now U.S. Pat No. 4,341,756. The stereoisomeric threitol can be prepared from the olefin employing conventional protective groups and conventional trans-addition, but the erythro derivative requires cis-addition which does not occur directly. Furthermore, with many synthetic sequences the presence of heterofunctionalities can lead to byproducts, including degradation products. It therefore becomes a difficult problem to find a synthetic approach which permits the employment of inexpensive starting materials to produce a highly functionalized compound in good yield substantially free of an undesired stereoisomer.
2. Description of the Prior Art
Cairns et al, J. Org. Chem., 17, 751 (1952) teaches the addition of positive chlorine and a nitrile across a double bond to produce a halo-amide. Co-pending application Ser. No. 141,097, filed Apr. 17th, 1980 has a description of the preparation of erythritylamine by inversion of threitylamine. Also disclosed in that application are X-ray contrast media employing the subject aminotetritols.