Crystal structure of N-{N-[N-(tert-but-oxy-carbon-yl)-l-α-aspart-yl]-l-α-aspart-yl}-l-α-aspartic acid 1(4),2(4),3(4)-trimethyl ester 3(1)-2-oxo-2-phenyl-ethyl ester {Boc-[Asp(OMe)](3)-OPac}.

In the title homotripeptide {Boc-[Asp(OMe)](3)-OPac}, C(28)H(37)N(3)O(13), all peptide bonds adopt an s-trans conformation with respect to the N-H and C=O groups. In the crystal, N-H⋯O hydrogen bonds result in an infinite parallel β-sheet structure running along the b-axis direction. The Boc protecting group at the N-terminus of the peptide is disordered over two sites with occupancy factors of 0.504†(5) and 0.496†(5).