Cilengitide is synthesized using solid-phase Merrifield-type methods by sequentially adding N-Boc-N-Me-L-Val (I), N-Boc-D-Phe (III), N-Boc-4-O-t-Bu-L-Asp (V), N-Boc-Gly (VII) and Nalpha-Fmoc-Nomega-Mtr-L-Arg (IX) in a stepwise manner to a 4-hydroxymethylphenoxymethyl-polystyrene resin (Wang type resin), yielding peptide-resin intermediates (II), (IV), (VI), (VIII) and (X), respectively. Elimination of the resin from the peptide chain with a 1:1 mixture of TFA/dichloromethane results in the linear peptide (XI), which is then deprotected at the amino-terminal group by removing the Fmoc group with a 1:1 mixture of piperidine/DMF, to give peptide (XII).

Cyclization of (XII) by means of DPPA in DMF/dichloromethane affords the cyclic peptide (XIII), which is finally deprotected by treatment with TFA/water 98:2.

Cilengitide is synthesized using solid-phase Merrifield-type methods by sequentially adding N-Boc-N-Me-L-Val (I), N-Boc-D-Phe (III), N-Boc-4-O-t-Bu-L-Asp (V), N-Boc-Gly (VII) and Nalpha-Fmoc-Nomega-Mtr-L-Arg (IX) in a stepwise manner to a 4-hydroxymethylphenoxymethyl-polystyrene resin (Wang type resin), yielding peptide-resin intermediates (II), (IV), (VI), (VIII) and (X), respectively. Elimination of the resin from the peptide chain with a 1:1 mixture of TFA/dichloromethane results in the linear peptide (XI), which is then deprotected at the amino-terminal group by removing the Fmoc group with a 1:1 mixture of piperidine/DMF, to give peptide (XII).

Cyclization of (XII) by means of DPPA in DMF/dichloromethane affords the cyclic peptide (XIII), which is finally deprotected by treatment with TFA/water 98:2.