Water → 1-(Pyridin-4-yl)propan-2-ol

To a stirred solution of 4-(2'-oxopropyl)-pyridine (13.7 g) in methanol (135 ml), sodium borohydride (3.0 g) was added in portions. After stirring for 2 hours, the mixture was taken to dryness in vacuo. The residue was distributed between ethyl acetate and a minimum of water sufficient to dissolve inorganic salts. The organic phase was dried and evaporated to yield 4-(2'-hydroxypropyl)-pyridine as a colourless oil. The oil was dissolved in acetic acid (100 ml) and hydrogenated in the presence of Adam's catalyst (1 g) until 3 equivalents of hydrogen were consumed. The catalyst was removed by filtration and the filtrate was concentrated in vacuo to yield crude 4-(2'-hydroxypropyl)-piperidine which was used directly in the next step. In analogous manner 4-(2'-hydroxybutyl)-piperidine was prepared from 4-(2'-oxobutyl)-pyridine.