CarbaMic acid, [(1S)-3-Methyl-1-(2-Methylpropyl)-2-oxo-3-butenyl]-, 1,1-diMethylethyl ester (9CI)

tert-Butyl ((S)-2,6-Dimethyl-3-oxohept-1-en-4-yl)carbamate is an intermediate in the synthesis of (S)-2-Amino-4-methyl-1-((S)-2-methyloxiran-2-yl)pentan-1-one Trifluoroacetate Salt which is an impurity of carfilzomib (C183460). Carfilzomib is a second-generation proteasome inhibitor that is used as a treatment in relapsed and refractory multiple myeloma.