the present invention provides a process for preparing a peptide of formula i ): sub --- a - c ] p —] n + m — oh comprising : reacting an immobilized compound of formula : sub --- a - c ] p —] n — oh with an amino acid ester or peptide derivative of formula : h —] m — o in the presence of a coupling agent to yield a peptide compound of general formula : sub --- a - c ] p —] n + m — o ; removing the tbu group to produce a solid - support bound carboxylic acid or peptide derivative of general formula ; wherein n is a positive integer , e . g ., 1 – 10 , preferably 1 – 5 ; m is a positive integer , and p is 0 – 1 .