1.41 g (10.2 mmol) of 4-hydroxybenzoic acid and 3 g (10.2 mmol) of (1.1) were suspended in 25 ml of DMF. 1.38 g (10.2 mmol) of 1-hydroxy-benzotriazole (HOBt) and, at 0° C., dicyclohexylcarbodiimide (DCCI) were added. The mixture was stirred at 0° C. for 1 h and allowed to stand at room temperature overnight. After filtration, the solvent was removed in vacuo and the residue was chromatographed on silica gel by means of MPLC using heptanelethyl acetate (1/1). (1.2) was obtained as a colorless solid; melting point 69° C.
