Vibegron Impurity 8

tert-Butyl ((1R,2R)-1-hydroxy-6-(4-nitrophenyl)-1-phenylhex-5-yn-2-yl)carbamate; 
Carbamic acid, N-[(1R)-1-[(R)-hydroxyphenylmethyl]-5-(4-nitrophenyl)-4-pentyn-1-yl]-, 1,1-dimethylethyl ester; 1,1-Dimethylethyl N-[(1R)-1-[(R)-hydroxyphenylmethyl]-5-(4-nitrophenyl)-4-pentyn-1-yl]carbamate;