The title compound has been synthesized by two related methods. Coupling of N-Boc-L-methylhistidine (I) with D-4-methoxyphenylalanine methyl ester (II) employing EDC/HOBt affords the protected dipeptide (III). Subsequent saponification of the methyl ester (III) leads to carboxylic acid (IV). This is then coupled to 4-butyryl-4-phenylpiperidine (V) to furnish amide (VI). Finally, acidic cleavage of the N-Boc protecting group of (VI) provides the title compound.

The title compound has been synthesized by two related methods. Coupling of N-Boc-L-methylhistidine (I) with D-4-methoxyphenylalanine methyl ester (II) employing EDC/HOBt affords the protected dipeptide (III). Subsequent saponification of the methyl ester (III) leads to carboxylic acid (IV). This is then coupled to 4-butyryl-4-phenylpiperidine (V) to furnish amide (VI). Finally, acidic cleavage of the N-Boc protecting group of (VI) provides the title compound.

Similarly, N-Boc-D-4-methoxyphenylalanine (I) is coupled to 4-butyryl-4-phenylpiperidine (II), yielding amide (III). After acidic Boc group cleavage in (III), the resultant amine (IV) is acylated by N-Boc-L-methylhistidine (V) to provide the dipeptide amide (VI). The N-Boc protecting group of (VI) is finally removed employing trifluoroacetic acid.