6-[(Difluoromethyl)oxy]-1-(4-piperidinyl)-1,3-dihydro-2H-benzimidazol-2-one hydrochloride (D54, 0.3 g) 1,2-dichloroethane (10 ml) and triethylamine (0.5 ml), tetrahydro-4H-pyran-4-one (0.6 g), sodium triacetoxyborohydride (0.6 g) was stirred at room temperature over 3 days. The mixture was poured into sodium bicarbonate solution and extracted with dichloromethane. The organic phase was separated, washed with brine and the solvent was removed and the residue was chromatographed on silica gel eluted with dichloromethane/2M ammonia in methanol 0-10%. The resulting product was dissolved in a mixture of methanol and dichloromethane, treated with 1M hydrogen chloride in ether and the solvent was removed. Recrystallisation from methanol gave the title compound as a white solid (0.26 g). Mass Spectrum 368 M+H+
