To a two-neck round bottom flask was added (1R,3S)-1-amino-3-(4-bromo-phenyl)-cyclopentanecarboxylic acid methyl ester; hydrochloride (3.94 g, 0.0118 mol), 1-octyne (3.48 mL, 0.0235 mol), triphenylphosphine (0.309 g, 0.00118 mol), piperidine (6.99 mL, 0.0706 mol), and THF (100 mL, 1 mol). The mixture was degassed, and Pd(PPh3)2Cl2 (0.41 g, 0.00059 mol) was added and the mixture was stirred for a few minutes under an atmosphere of nitrogen before addition of the copper(I) iodide (0.11 g, 0.00059 mol). The reaction was stirred under an atmosphere of nitrogen at 60° C. for 2 hours. More 1-octyne (12 mL, 0.081 mmol) was added in 3 portions. The reaction mixture was heated at 60° C. for a total of about 36 hours. The solvent was then removed and crude material was partitioned between EtOAc and saturated NaHCO3. The aqueous layer was back-extracted once with EtOAc. Organic layers were combined, dried over MgSO4 and the solvent was removed under reduced pressure. The residue was purified by silica gel chromatography using 1 L of EtOAc followed by 1 L of 2% MeOH in EtOAc to give 3.38 g crude product as a yellow oil. The crude product was dissolved in minimum amount of MeOH, to which L-tartaric acid (1.69 g) in MeOH was added. Ether was then added dropwise until solution just turned turbid. The mixture was left to crystallize. The solid was collected by filtration, washed with ether to give 3.91 g (72.6%) (1R,3S)-1-amino-3-(4-prop-1-ynyl-phenyl)-cyclopentanecarboxylic acid methyl ester; compound with (2R,3R)-2,3-dihydroxy-succinic acid.
