Peptide synthesis. Part 12. 3,4-Dihydro-4-oxo-1,2,3-benzotriazin-3-yl esters of fluorenylmethoxycarbonyl amino acids as self-indicating reagents for solid phase peptide synthesis

The preparation and characterisation of 3,4-dihydro-4-oxo-1,2,3-benzotriazinyl esters (1) of Fmoc-amino acids and their use in solid phase peptide synthesis is described. Ionisation of the liberated hydroxy component (2) by the starting resin-bound amine provides a useful colour indicator of the progress of acylation reactions.