Process for the preparation of 5-substituted 2-chloropyridines

摘要

Prepn. of 5-substd. 2-chloropyridines of formula (I) comprises (1) reacting acetenamides of formula (II) with Vilsmeier reagent (III), which is prepd. by reacting formamides of formula (IV) with a chlorinating agent (V); and (2) removing excess (V) after reaction by distn. or addn. of dialkylformamide: R = opt. substd. (ar)alkyl; R1 = 1-4C alkyl or aryl-(1-4C)-alkyl; R2,R3 = linear, branched or cyclic 4-8C alkyl.