Protection of L-glutamic acid (I) with allyl alcohol and chlorotrimethylsilane produced the gamma-allyl ester (II). Subsequent treatment of (II) with fluorenylmethoxycarbonyl chloride afforded the N-Fmoc derivative (III). This was coupled to Wang resin using EDC and DMAP to provide the glutamate-coupled resin (IV). Removal of the Fmoc protecting group by means of piperidine gave (V), which was then condensed with decanoyl chloride (VI) yielding amide (VII). The allyl ester was then cleaved by treatment with Pd(PPh3)4 and the resulting carboxylic acid (VIII) was coupled with monoprotected diamine (IX) to furnish diamide (X). Deprotection of the allyl carbamate of (X) provided amine (XI).

Amine (XI) was coupled to isoxazolecarboxylic acid (XII) to give (XIII). which was finally liberated from the resin by cleavage with trifluoroacetic acid in CH2Cl2.

Protection of L-glutamic acid (I) with allyl alcohol and chlorotrimethylsilane produced the gamma-allyl ester (II). Subsequent treatment of (II) with fluorenylmethoxycarbonyl chloride afforded the N-Fmoc derivative (III). This was coupled to Wang resin using EDC and DMAP to provide the glutamate-coupled resin (IV). Removal of the Fmoc protecting group by means of piperidine gave (V), which was then condensed with decanoyl chloride (VI) yielding amide (VII). The allyl ester was then cleaved by treatment with Pd(PPh3)4 and the resulting carboxylic acid (VIII) was coupled with monoprotected diamine (IX) to furnish diamide (X). Deprotection of the allyl carbamate of (X) provided amine (XI).

Amine (XI) was coupled to isoxazolecarboxylic acid (XII) to give (XIII). which was finally liberated from the resin by cleavage with trifluoroacetic acid in CH2Cl2.