A synthesis of the acetal of dl‐pelletierine or β‐(2‐piperidyl)‐propionaldehyde acetal.

Abstract In the catalytic hydrogenation of β‐(2‐pyridyl)‐propionaldehyde acetal (I) in a solution of pure acetic acid with a platinum catalyst according to Adams the following substances may be formed as addition compounds with acetic acid: the δ‐coniceine of Löffler (III) and the β‐(2‐piperidyl)‐propionaldehyde acetal or the acetal of dl‐pelletierine (II). The latter compound is obtained almost exclusively when a very concentrated solution of I in acetic acid is subjected to catalytic reduction. The acetal of dl‐pelletierine is a stable colourless liquid. Upon hydrolysis of this acetal a liquid with a strong reducing action is obtained which is rapidly converted into a reddish resin, corresponding to the behaviour of dl‐pelletierine as described in the literature.