Patent ID: 6852887

Claim:
A process for preparing a compound having the following general formula: said process comprising: (a) combining a compound of Formula II with an aromatic solvent/alkyl acetate to form a reaction mixture and heating said reaction mixture, said compound of Formula II having the following general formula: (b) treating said reaction mixture with an acid having a pK a of less than about 4 until the reaction is complete, thereby forming said compound of Formula III; wherein: R 1 is an amino acid side chain or a functionalized amino acid side chain; R 2 is a protecting group; R 3 is a member selected from the group consisting of hydrogen, alkyl, cycloalkyl, aryl and —NHP, wherein P is selected from the group consisting of H, alkyl, cycloalkyl, aryl and a protecting group; and X − is the conjugate base of said acid.