A symposium report on stability, reactivity and solubility of urethane-protected amino acid N-carboxyanhydrides.The stability of the N-carboxyanhydrides of Fmoc-X-OH [X = Ala, Aib, Arg(Pmc), Asn(Trt), Asp(OCMe3), Cys(Trt), Leu, Lys(Boc), Thr(CMe3), Arg(Mtr), Ile, Val] and Boc-X1-OH [X1 = Ala, Asp(OBzl),Glu(OBzl), Gln(Trt), His(Dnp), Leu, Phe, Thr(Bzl), Tyr(Bzl), Aib. Arg(Tos), Cys(MeOBzl), Glu(OBzl), Gln(Trt), Gly, Val] in THF or DMF were determined