Silver acetate (1.3 g) was added to a solution of 3-(4-hydroxyphenyl)propylamine hydrochloride (1.2 g) and N,N'-Bis(tert-butoxycarbonyl)-S-methylisothiourea (1.86 g) in DMF (10 mL) containing triethylamine (3.0 g). The mixture was stirred for 3 hr, and an additional 1.0 g silver acetate was added. After one hour, the mixture was diluted with ethyl acetate, filtered through Celite, washed with water, dried over magnesium sulfate, and the solution evaporated. Chromatography on silica gel with 20% ethyl acetate in hexane provided the title compound as a white solid, mp 142°-144° C. (dec) after recrystallization from hexane-ethyl acetate (2.1 g, 77%).
