Fmoc, 9-fluorenylmethoxycarbonyl side reactions

The application of additives was investigated in order to suppress or diminish side reactions (A-acyl urea formation and racemization). Al-Hydroxysuccinimide (HOSu), 1-hydroxybenzotriazole (HoBt), and ethyl l-hydroxy-lH-l,2,3-triazole-4-carboxylate are potential additives in the DCC-based coupling synthesis. Solid-phase peptide synthesis (SPPS) is a variant of the linear (stepwise) coupling of amino acids in the C N direction using two major protection groups Boc/Bzl (iert-butoxycarbonyl/benzyl) and Fmoc/tBu (/9-fluorenylmethoxycarbonyl/ieri-butyl). The synthetic scheme for peptides on a polymer (Atherton and Sheppard, 1989 Fields, 1997) is illustrated in Figure 8.1. 

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