Solid phase process for synthesizing thymosin alpha 1

摘要

4-methyloxybenzyloxycarbonyl (Moz) is used to protect the alpha amino groups of the amino acids used in solid-phase synthesis of thymosin alpha 1. It was found that the Moz group can be removed rapidly and completely with 5-10% trifluoroacetic acid in CH2Cl2. Some advantages of utilizing Moz-amino acids over Boc-amino acids in solid-phase peptide synthesis are higher yields and purities with reduced consumption of trifluoroacetic acid during the acidolytic cleavage of the N alpha -Moz groups. Further improvements with respect to the recovery and recycling of the used solvent are obtained by using tributylamine in place of triethylamine as the neutralization agent making it possible to distill methylene chloride from the liquid waste without contamination by the lower boiling triethylamine. Methylbenzhydrylamine resin is the preferred resin support. Cleavage from the resin support and deprotection of the protected side groups of the protected thymosin alpha 1 can be accomplished using either HBr or trifluoromethane sulfonic acid in trifluoroacetic acid with anisole and thioanisole as scavengers.