Atosiban Impurity 24

(S) -1- ((4R,7S,10S,13S) -7- (2-amino-2-oxoethyl) -14- ((R) -2-amino-3- (4-ethoxyphenyl) propanoyl) -13- ((S) -sec-butyl) -10- ((R) -1-hydroxyethyl) -6,9,12,15-tetraoxo-1,2-dithia-5,8,11,14-tetraazacycloheptadecane-4-carbonyl) -N- ((R) -2-oxopiperidin-3-yl) pyrrolidine-2-car