Patent ID: 6899912

Claim:
Crystalline N-[N-[3-(3-methoxy-4-hydroxyphenyl)propyl]-L-α-aspartyl]-L-phenylalanine 1-methyl ester, which is prepared by a process comprising: (1) subjecting N-L-α-aspartyl-L-phenylalanine 1-methyl ester and 3-(3-methoxy-4-hydroxyphenyl)propionaldehyde or a derivative thereof to reductive alkylation in a solvent to obtain N-[N-[3-(3-methoxy-4-hydroxyphenyl)propyl]-L-α-aspartyl]-L-phenylalanine 1-methyl ester; and (2) crystallizing said N-[N-[3-(3-methoxy-4-hydroxyphenyl)propyl]-L-α-aspartyl]-L-phenylalanine 1-methyl ester, wherein said reductive alkylation comprises catalytic hydrogenation, wherein said derivative thereof is selected from the group consisting of 3-(3-methoxy-4-hydroxyphenyl)-2-propenylaldehyde, 3-(3-methoxy-4-protected-hydroxyphenyl)propionaldehyde, 3-(3-methoxy-4-protected-hydroxyphenyl)-2-propenylaldehyde, and acetals derived therefrom, and wherein said crystalline N-[N-[3-(3-methoxy-4-hydroxyphenyl)propyl]-L-α-aspartyl]-L-phenylalanine 1-methyl ester exhibits X-ray diffraction peaks at 2θ diffraction angles of 5.55°, 12.25°, 18.5°, 21.1° and 22.45° with CuKα rays.