31 mg (0.199 mmol) of (1R,2S,3R)-3-aminocyclopentane-1,2-diol are dissolved in 3.5 ml of THF and 2 ml of DMF, and 33.8 μl of DIPEA are added. 80 mg (0.199 mmol) of 6′-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydronaphthalen-2-yl)-2,3,5,6-tetrahydro-1,2′-bipyridinyl-4-one are added. The mixture is stirred at room temperature for 30 min, 23 μl (0.398 mmol) of glacial acetic acid are added, and the mixture is stirred for a further 10 min. 89 mg (0.398 mmol) of sodium triacetoxyborohydride are subsequently added. The reaction mixture is stirred at room temperature overnight, a concentrated sodium hydrogencarbonate solution is added, and the mixture is extracted twice with EA. The organic phase is dried over sodium sulfate, filtered and evaporated. The residue is purified by means of preparative HPLC. The product is in the form of the hydrochloride.
