Syntheses of [14C]-labeled 2-(3-chlorophenyloxy)-3-[3-(3-hydroxy) pyridin-4-yl propoxy]pyridine, a phosphodiesterase 4 inhibitor and its metabolites.

We describe here the synthesis of [(14)C]-2-(3-chlorophenyloxy)-3-[3-(3-hydroxy)pyridin-4-yl propoxy]pyridine (1), a phosphodiesterase 4 inhibitor. [(14)C]-Labeled 1 was prepared in three steps from [(14)C]-2-bromopyridin-3-ol in an overall yield of 32%. Preparation of [(14)C]-labeled 2 and 3, two metabolites of 1, is also described.