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with piperidine were obtained. For checking the t-BuNH 2 scope, limitation and diversity,we checked it for the synthesis of Leu- and Met-enkephalin (Figure 1). The results werecomparable to piperidine.In conclusion, t-BuNH 2 solution in DMF could be used instead of piperidine in DMFin SPPS for Fmoc group removal from the resin-bound peptides. This can provideconvenience and lower cost peptide synthesis because piperidine is not only an expensivereagent but also is a controlled substance. Meanwhile the diversity of this methodology waschecked using different protected amino acids.ClClFmoc-A.A -OH, DIPEADMF, DCM2) Fmoc-Phe-OH, TBTUDIPEA, DMF(25%), DMF 1) t-BuNH 2 (25%), DMF2) Fmoc-Gly-OH, TBTUDIPEA, DMF1) t-BuNH 2 (25%), DMF2) Fmoc-Gly-OH, TBTUDIPEA, DMF1) t-BuNH 2Fmoc-Gly-Gly-Phe-(A.A)-Fmoc-Tyr(tBu)-Gly-Gly-Phe-(A.A)-t-BuNH 2 (25%), DMFTFA(1%), DCM1) t-BuNH 2 (25%), DMFH-Tyr(tBu)-Gly-Gly-Phe-(A.A)-OH2) Fmoc-Tyr(tBu)-OH, TBTUDIPEA, DMFTFA:TES:H2O(94:5:1)PurificationH-Tyr-Gly-Gly-Phe-(A.A)-OHFig. 1. Solid phase synthesis of enkephalins by using of t-BuNHA.A = Met,Leu2 for Fmoc-deprotection.Table 2. Fmoc-deprotection using t-BuNH 2 for Fmoc-Met-ResinBaseFmoc-deprotection (%)T=2 min T=5 min T=10 min T=20 min5% 51.2 79.5 89.8 96.1Piperidine/DMFt-Butylamine/DMF10% 76.2 82.4 91.1 97.625% 81.4 94.2 97.6 100.05% 29.1 48.5 66.2 90.010% 32.3 62.5 78.3 96.125% 60.7 81.6 88.4 100.0AcknowledgmentsWe would like to thank Tofigh Daru Research & Eng. Co. for kind cooperation. A part of this researchwork was supported by research council of K. N. Toosi University of Technology is gratefullyacknowledgedReferences1. Moroder, L., Felix, A., Toniolo, C. (Eds.) Synthesis of Peptides and Peptidomimetics, Vol E 22a,Thieme, Stuttgart, 2004.2. Leondiadis, L., Zinieris, N., Ferderigos, N. J. Comb. Chem. 7, 4-6 (2005).3. Suarez-Castillo, O.R., Montiel-Ortega, L.A., Melendez-Rodriguez, M., Sanchez-Zavala, M. Tet.Lett. 48, 17-20 (2007).51