| abstract |
Disclosed are preferred processes for the preparation of 2-halo-nicotinic acid derivatives of formula (IV) by cyclocondensation of a 4-halo-4-cyanocarbonyl compound of formula (III) wherein X is Cl or Br; Y is a carbonyl group and R?1, R2 and R3¿ are each, independently, H, Cl, Br or an organic radical. Further preferred aspects include the preparation of the above-noted 4-halo-4-cyanocarbonyl compound via Michael addition of a 2-halonitrile with an α,β-unsaturated aldehyde or ketone, and the preparation of the 2-halonitrile by redistribution of halogen between a 2,2-dihalonitrile and a parent nitrile. |