Stereochemically controlled synthesis of diethylenetriaminepentaacetic acid (DTPA) analogues substituted on the ethylene backbones with methyl groups, the chiral center a to the terminal nitrogen being derived from (SI-or (R)-alanine, has been achieved. The key intermediate (5')-propylenediaminetriacetic acid triester was synthesized via selective detosylation of the alkylation product derived from (SI-alanine and tert-butyl glycinate. ...
