A mixture of 2-(S)-amino-pentanoic acid (5-isopropyl-thiazol-2-yl)-amide (350 mg, 1.4 mmol) and 2-tetralone (318 mg, 2.2 mmol)in 20 mL of methylene chloride and 5 drops of acetic acid was treated with sodium triacetoxyborohydride (462 mg, 2.2 mmol) and stirred at room temperature overnight. The mixture was concentrated and eluted through SPEC SCX cartridge and concentrated to dryness. The residue was purified by silica gel column chromatography to give 2-(S)-(1,2,3,4-Tetrahydro-naphthalen-2-ylamino)-pentanoic acid (5-isopropyl-thiazol-2-yl)-amide as a solid, LC-MS, RT=1.9 min, M+1=372.
