Useful Intermediates for Synthesis of Dicarba Analogues of Cystine Peptides: Selectively Protected α-Aminosuberic Acid and α,α'-Diaminosuberic Acid of Defined Stereochemistry

Article abstract of DOI:10.1021/jo01303a028

Practical procedures are described for synthesis of selectively protected α-aminosuberic acid and α,α'-diaminosuberic acid by the mixed Kolbe electrolytic decarboxylative dimerization of two different carboxylic acids.Stereochemistry is established by the choice of L- or D-glutamic acid precursors.The method is illustrated by the synthesis of α-tert-butyl N^α-Boc-N^α'-Cbz-LL-α,α'-diaminosuberate (6) and α-tert-butyl ω-methyl N^α-Boc-D-α-aminosuberate (10) which can be used directly in the preparation of dicarba and desaminodicarba analogues of cystinepeptides.Although statistically controlled mixtures are produced, facile procedures for isolation of the products have been worked out.No racemization of chiral centers was detected.