A new base-labile carboxyl protecting group, the 2-(4-acetyl-2-nitro-p
henyl)ethyl (Anpe) group is reported and compared with other base-labi
le protecting groups. The synthesis of the alcohol precursor, 1-[4-(2-
hydroxyethyl)-3-nitrophenyl]-1-ethanone, the amino acid derivatives Bo
c-Asp(Anpe)-OH and Boc-Glu(Anpe)-OH and the conditions under which the
carboxyl protecting group can be eliminated are also described.