0.5 ml (3 mmol) of triethylamine are added to a solution containing 0.5 g (3 mmol) of 3-hydroxy-3-(1H-imidazol-4-yl)propanoic acid and 1.0 g (3 mmol) of TBTU in 2 ml of dimethylformamide. After stirring for 1 h at ambient temperature, 1.5 g (3 mmol) of (R)-2-amino-1-(3-butoxy-3-o-tolylazetidin-1-yl)-3-(4-methoxyphenyl)-propan-1-one hydrochloride (prepared as described in Example 6.2) are added. The reaction medium is stirred for 24 h at ambient temperature, treated with a 1N aqueous solution of sodium hydroxide and extracted with a 20/80 heptane/ethyl acetate mixture. The organic phase is dried over magnesium sulphate, filtered and concentrated. The product is purified by silica gel chromatography, elution being carried out with a 97/3 dichloromethane/methanol mixture. 72 mg of N—[(R)-2-(3-butoxy-3-o-tolylazetidin-1-yl)-1-(4-methoxybenzyl)-2-oxoethyl]-3-hydroxy-3-(1H-imidazol-4-yl)propionamide are obtained in the form of a beige powder with a yield of 5%.
