A solution of N-(3,3-diethoxypropyl)-N-phenethyl-3-phenethyloxy-propanamide (Example 8b), 0.127 g) in dioxane (10 mL) was treated with concentrated hydrochloric acid (1 mL) and stirred at room temperature for 30 minutes. After this time the solution was diluted (dichloromethane 30 mL), washed with water (2×20 mL), brine (20 mL), dried over magnesium sulfate and concentrated to give the crude aldehyde product (0.13 g) which was used immediately. The crude aldehyde was dissolved in methanol (20 mL) and 7-(2-aminoethyl)-4-hydroxy-3H-benzothiazol-2-one hydrochloride (0.078 g) was added along with acetic acid (0.1 mL) and water (0.1 mL). After stirring at room temperature for 30 minutes, sodium cyanoborohydride (0.012 g) was added and the reaction mixture stirred overnight. Ammonia (7N in methanol, 1 mL) was added and the mixture was concentrated. The resulting residue was taken up in ethyl acetate (50 mL), washed with water (2×20 mL), brine (20 mL), dried over magnesium sulfate and concentrated to give the crude product which was purified by flash column chromatography eluting with 1% ammonia; 5% methanol in dichloromethane to afford the titled compound as a white solid (0.078 g).
