Regioselective conversion of 3‐cyano‐6‐hydroxy‐2‐pyridones into 3‐cyano‐6‐amino‐2‐pyridones

The reaction of a tautomeric mixture of 1‐butyl‐1,2‐dihydro‐6‐hydroxy‐4‐methyl‐2‐oxopyridine‐3‐carbonitrile and its 2‐hydroxy‐6‐oxo analog with phosphorus oxychloride gave 1‐butyl‐6‐chloro‐1,2‐dihydro‐4‐methyl‐2‐oxopyridine‐3‐carbonitrile (68%) and 1‐butyl‐2‐chloro‐1,6‐dihydro‐4‐methyl‐6‐pyridine‐3‐car‐bonitrile (3%). Both chloropyridones were converted to their corresponding aminopyridones by reaction with liquid ammonia. Strong support for the molecular structure of 6‐amino‐1‐butyl‐1,2‐dihydro‐4‐methyl‐2‐oxopyridine‐3‐carbonitrile was obtained on the basis of nmr techniques.