Etelcalcetide Impurity 6

Ac-D-Cys (Ac-Cys-D-Ala-D-Arg-D-Arg-D-Arg-D-Ala-D-Arg-NH2) -D-Ala-D-Arg-D-Arg-D-Arg-D-Ala-D-Arg-NH2; N, N'- ((6R,9R,12R,15R,18R,21R,24R,29S,32R,35R,38R,41R,44R,47R) -1,1,52,52-tetraamino-6,47-dicarbamoyl-12,15,18,35,38,41-hexakis (3- ((diaminomethylene) amino) propyl) -9,21,32,44-tetramethyl-8,11,14,17,20,23,30,33,36,39,42,45-dodecaoxo-26,27-dithia-2,7,10,13,16,19,22,31,34,37,40,43,46,51-tetradecaazadopentaconta-1,51-diene-24,29-diyl) diacetamide