Vibegron Impurity 4

Tert-butyl (4R,5R)-4-(hydroxymethyl)-2,2-dimethyl-5-phenyloxazolidine-3-carboxylate; 
3-Oxazolidinecarboxylic acid, 4-(hydroxymethyl)-2,2-dimethyl-5-phenyl-, 1,1-dimethylethyl ester, (4R,5R); 1,1-Dimethylethyl (4R,5R)-4-(hydroxymethyl)-2,2-dimethyl-5-phenyl-3-oxazolidinecarboxylate; Tert-Butyl (4R,5R)-4-(Hydroxymethyl)-2,2-Dimethyl-5-Phenyl-1,3-Oxazolidine-3-Carboxylate;