Vibegron Impurity 6

Carbamic acid, N-[(1S)-1-benzoyl-4-pentyn-1-yl]-, 1,1-dimethylethyl ester; 
1,1-Dimethylethyl N-[(1S)-1-benzoyl-4-pentyn-1-yl]carbamate; (S)-tert-Butyl (1-oxo-1-phenylhex-5-yn-2-yl)carbamate;Tert-butyl (S)-(1-oxo-1-phenylhex-5-yn-2-yl)carbamate