(1R,2S,5S)-N-(4-amino-1-cyclobutyl-3,4-dioxobutan-2-yl)-3-[(2S)-2-(tert-butylcarbamoylamino)-3,3-dimethylbutanoyl]-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide (1R,2S,5S)-N-[3-amino-1-(cyclobutylmethyl)-2,3-dioxo-propyl]-3-[(2S)-2-(tert-butylcarbamoylamino)-3,3-dimethyl-butanoyl]-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide (1R,2S,5S)-N-[3-amino-1-(cyclobutylmethyl)-2,3-dioxopropyl]-3-[(2S)-2-[[(tert-butylamino)-oxomethyl]amino]-3,3-dimethyl-1-oxobutyl]-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide (1R,2S,5S)-N-[3-amino-1-(cyclobutylmethyl)-2,3-diketo-propyl]-3-[(2S)-2-(tert-butylcarbamoylamino)-3,3-dimethyl-butanoyl]-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide (1R,2S,5S)-N-(4-amino-1-cyclobutyl-3,4-dioxo-butan-2-yl)-3-[(2S)-2-(tert-butylcarbamoylamino)-3,3-dimethyl-butanoyl]-6,6-dimethyl-3-azabicyclo[3.1.0]hexane-2-carboxamide SCH503034