Secondary alcohols were converted to their corresponding esters with N-Cbz-L-amino acids by Celite-immobilized protease or lipase in organic solvents at pH 7.5. The esterification of 2-butanol and 2-phenylethanol were achieved up to 71% yields. The optimal reaction condition for Aspergillus oryzae protease (AOP) catalyzed synthesis of N-Cbz-L-aspartyl-sec-butyl ester (97.6 de) was at pH 7.5 and a duration of 96 hours.