A New Base‐Labile Anchoring Group for Polymer‐Supported Peptide Synthesis

A new base‐labile anchoring group, derived from 9‐(hydroxymethyl)fluorene‐4‐carboxylic acid (HO2CFmoH or HOFmCO2H; 7), for polymer‐supported peptide synthesis os described. The synthesis of 7 starting from 2,2′‐biphenyldicarboxylic acid (1) proceeds in an overall yield of 53%. The group HO2CFmo exhibits properties similar to the well known Fmoc protecting group: It is stable to acidic conditions and cleavable by 15% piperidine in DMF. In combination with acid labile Nα‐protecting groups (e.g. Boc, Ddz, Bpoc, Nps etc.), it renders more flexibility to the stepwise synthesis using polymer supports. The versatility of the new anchoring group in solid‐ and liquid‐phase peptide synthesis is demonstrated for the synthesis of a model peptide.