Use of a Removable Backbone Modification Strategy to Prevent Aspartimide Formation in the Synthesis of Asp Lactam Cyclic Peptides†.

Main observation and conclusion: The synthesis of an Asp lactam derivative of A‐183, a selective inhibitor of Factor 7a with good anticoagulant and antithrombotic activity, is described. Our synthesis depends on the use of a removable backbone modification (RBM) strategy to prevent aspartimide formation, which thwarted all attempts to synthesize this target using direct solid‐phase peptide synthesis. Validation of the RBM strategy in the synthesis of a second Asp lactam derivative was also accomplished. The RBM strategy is therefore proposed as a general method for the synthesis of Asp lactam cyclic peptides. [ABSTRACT FROM AUTHOR]