Patent ID: 7301006

Claim:
A protected amino acid useful for synthesis of a selectively derivatized peptide which has the formula: and salts thereof wherein: * indicates that the indicated C may be chiral, non-racemic or racemic; PR is any appropriate amine protecting group wherein the conditions for removal of the protecting group are substantially orthogonal to the conditions for removal of the azide-bearing protecting group; R′ is OH, OR, OAr, NH 2 , NH(R or Ar), NR 2 , N(Ar) 2 , a group that generates an activated ester, a halogen, a substituted phenyl group, a halogenated phenyl group, benzotriazol-1-yl, N-hydroxysuccinimido, or 3,4-dihydro-4-oxo-1,2,3-benzotriazin-3-yl, where Ar is an optionally substituted aryl group, and where Ar is an aryl group other than an aryl group that contains an alkyl portion; R is H or alkyl, A is an optionally substituted phenyl group; n is 0 or 1; and M is selected from the group consisting of: —(CH 2 ) m — where m is 1-6; —CH 2 -phenyl- wherein the phenyl can be optionally substituted; —CH 2 -phenyl-O— wherein the phenyl can be optionally substituted; —(CR 2 ) m where m is 1-6, each R selected independently of other R; —CO—NH—SO 2 —CH 2 —CH 2 —; and —CO—NH—CH 2 —CH 2 —.