To obtain the subject compound useful as a starting material for a variety of pyridine compounds important in the medicinal and agrochemical fields in a high yield from easily available materials, by reacting a specified pyridine with a halogenating agent.
This method compound of formula I (X is a halogen) is obtained by reacting (A) 5,5'-dicyano-2,2'-thiobispyridine with (B) a halogenating agent (e.g. chlorine) e.g. in the molar ratio B/A of 0.1 to 100, in such a solvent as acetonitrile at 20°C to the reflux temperature of the solvent. The component A is produced, preferably, by reacting 2-sulfonyl-5-cyanopyridine of formula II (R is an alkyl, cycloalkyl, etc.) with a metal sulfide (e.g. sodium sulfide), or a metal hydrosulfide (e.g. sodium hydrosulfide) plus a metal hydroxide (e.g. sodium hydroxide) in the presence of such a diluent as methanol at a temp. of -20 to 200°C.
ASANUMA GORO
INOUE SHINICHI
SHIONO MANZO
