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The present investigation reports an attempt to synthesize naturally occurring α-cyclic tripeptide <i>cyclo</i>(Gly-<span style="font-variant: small-caps;">l</span>-Pro-<span style="font-variant: small-caps;">l</span>-Glu) <b>1</b>, [<i>cyclo</i>(GPE)], previously isolated from the <i>Ruegeria</i> strain of bacteria with marine sponge <i>Suberites domuncula.</i> Three linear precursors, Boc-GPE(OBn)₂, Boc-PE(OBn)G and Boc-E(OBn)GP, were synthesized using a solution phase peptide coupling protocol. Although <i>cyclo</i>(GPE) <b>1</b> was our original target, all precursors were dimerized and cyclized at 0 °C with high dilution to form corresponding α-cyclic hexapeptide, <i>cyclo</i>(GPE(OBn))₂<b>7</b>, which was then converted to cyclic hexapeptide <i>cyclo</i>(GPE)₂<b>2</b>. Cyclization at higher temperature induced racemization and gave cyclic tripeptide <i>cyclo</i>(GP_DE(OBn)<b>) 9</b>. Structure characteristics of the newly synthesized cyclopeptides were determined using ¹H-NMR, ¹³C-NMR and high-resolution mass spectrometry. The chemical shift values of carbonyls of <b>2</b> and <b>7</b> are larger than 170 ppm, indicating the formation of a cyclic hexapeptide.