A newone-pot procedure for the preparation of pentafluorophenyl and 3,4-dihydro-4-oxo-1,2,3-benzotriazine-3-ylesters of Nα-9-fluorenylmethyloxycarbonyl aminoacids bearing no side chain protecting groups is described. The method gives the desired activated esters in high yield and purity without use of the highly allergenic DCC.