摘要:
Described are preferred processes for preparing 2-halo-5-substituted pyridine compounds. Preferred processes can be conducted in a one-step, one-pot fashion, and involve the reaction of a formamide and a halogenating agent with a nitrile such as cis-2-pentenonitrile or with a combination of reactants including an aldehyde such as n-propionaldehyde and a nitrile or an amide. Preferred processes provide for convenient and advantageous preparations of 2-chloro-5-methylpyridine, which serves as an intermediate to important insecticidal compounds.
摘要:
Disclosed are preferred processes for preparing a 2-halo-5-halomethylpyridine compound. The preferred processes involve cyclocondensing a 2-halo-2-halomethyl aldehyde or ketone of the formula (II) ##STR1## to form a 2-halo-2-halomethylpyridine compound of the formula (III) ##STR2## wherein X is Cl or Br, Y is a cyano group or an aminocarbonyl group, and R, R.sup.1, R.sup.2 and R.sup.3 are, independently, H or an organic radical which does not interfere with the cyclocondensation.
摘要:
Disclosed are preferred processes for the preparation of 2-halo-nicotinic acid derivatives of formula (IV): ##STR1## by cyclocondensation of a 4-halo-4-cyanocarbonyl compound of formula (III): ##STR2## wherein X is Cl or Br; Y is a carbonyl group and R.sup.1, R.sup.2 and R.sup.3 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 .alpha.,.beta.-unsaturated aldehyde or ketone, and the preparation of the 2-halonitrile by redistribution of halogen between a 2,2-dihalonitrile and a parent nitrile.