5 ml of a methanolic solution containing 0.26 g of a 28% w/v sodium methoxide solution were added, whilst ice-cooling, to a solution of 0.50 g of N-[4-(4-piperidinomethyl-2-pyridyloxy)-cis-2-butenyl]-2-(acetylthio)acetamide [prepared as described in step (b) above] in 5 ml of methanol, and the resulting solution was stirred for 20 minutes. At the end of this time, a solution of 0.11 ml of 3-chloro-1-propanol in 5 ml of methanol, was added, and the reaction mixture was heated under reflux for 5 hours. The solvent was then removed by distillation under reduced pressure. The residue thus obtained was mixed with water, and the aqueous mixture was extracted with ethyl acetate. The extract was concentrated by evaporation under reduced pressure, and the residue was purified by column chromatography through silica gel, using a 1:9 by volume mixture of methanol and methylene chloride as the eluent, to give 0.42 g (yield 81%) of the title compound as an oil.
