Crown Catalyzed Esterification of BOC-Amino Acid to Chloromethylated Resins

7 Crown Catalyzed Esterification of BOC-Amino Acids to Chloromethylated Resins 

The Merrifield solid phase peptide synthesis requires the formation of an esterified resin as the first step. The substitution of an N-protected amino acid for a chloride in chloromethylated polystyrene must be quantitative or products which are one amino acid too short will ultimately be isolated. 18-Crown-6 has been shown to catalyze quantitative ester formation between the potassium salts of boc-amino acids and chloromethylated resin in DMF solution. Dichloromethane was reactive under these conditions [26]. The results of these displacement reactions according to equation 6.10 are presented in Table 6.8. 

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