N-[(1R)-1-[(Methoxymethylamino)carbonyl]-3-methylbutyl]-carbamic Acid 1,1-Dimethylethyl Ester is an intermediate in synthesizing (R)-2-Amino-4-methyl-1-((S)-2-methyloxiran-2-yl)pentan-1-one Trifluoroacetate Salt (A605100), an impurity of carfilzomib (C183460). Carfilzomib is a second-generation proteasome inhibitor that is used as a treatment in relapsed and refractory multiple myeloma. Molecular Formula: C13H26N2O4 Molecular Weight: 274.36