| 摘要 |
<p>Process for the preparation of a 4-chloropyridine-N-oxide of formula (1) in which R?1, R2 and R3¿ each independently stand for H, an alkyl group or an alkoxy group and R4 stands for an alkyl group or an alkoxy group, in which the corresponding 4-H-pyridine-N-oxide is subjected to a treatment with Cl¿2?, resulting in the formation of 4-Cl-pyridine-N-oxide. Preferably R?1¿ stands for H, R2 stands for H or methyl, and R?3 and R4¿ both stand for CH¿3?, or R?1 and R2¿ both for H, R3 for methoxy and R4 for methyl. Preferably the chlorination is carried out in the presence of a base, for example an (earth) alkali metal hydroxide or carbonate, and water, and use is made of between 1 and 3 base equivalents, calculated relative to the quantity of 4-H-pyridine-N-oxide and 0 to 10 equivalents of water, calculated relative to the quantity of 4-H-pyridine-N-oxide. The 4-Cl-pyridine-N-oxide obtained can subsequently be subjected to a treatment with a substituted or unsubstituted alcohol in the presence of a base. The resulting compounds are suitable for use in the preparation of pharmaceuticals, for example omeprazol, pantoprazol, rabeprazol and lansoprasol.</p> |
