PROCESSES FOR PREPARATION OF 4-AMINO-3-HALO-6-(SUBSTITUTED)PICOLINATES AND 4-AMINO-5-FLUORO-3-HALO-6-(SUBSTITUTED)PICOLINATES Russian patent published in 2018 - IPC C07D213/79 C07D213/74 C07D213/73 C07C251/16 C07C251/12 A01N43/40 

FIELD: chemistry.

SUBSTANCE: invention relates to a process for the preparation of 4-amino-3-halogen-6-(substituted)picolinate of Formula I, which comprises the following steps: (a) contacting difluoroacetic acid or trifluoroacetic acid with tritylamine or tert-butylamine in the presence of triarylphosphine and a trialkylamine base in carbon tetrachloride as a solvent to obtain 2,2-difluoro- or 2,2,2-trifluoro-N-(trityl or t-butyl)ethanimidoyl chloride (Formula A); (b) contacting 2,2-difluoro- or 2,2,2-trifluoro-N-(trityl or isobutyl)ethanimidoyl chloride (Formula A) with 3,3-dialkoxyprop-1-yne (Formula B), where R⁴ is C₁-C₄ alkyl, in the presence of copper (I) iodide, an alkali metal iodide and an alkali metal phosphate in a polar aprotic solvent, to obtain (imino) pent-2-yl of dialkyl acetal of Formula C; (c) cyclisation of (imino)pent-2-yne of a dialkyl acetal of Formula C with an amine R¹-CH₂-NH₂ of Formula D, in the presence of an inorganic base of an alkali metal in a polar aprotic solvent at a temperature from about ambient temperature to about 100°C to obtain trityl- or isobutyl-protected 4-amino-6-(substituted)pyridine-2-dialkylacetal of Formula E; (d) deprotection and hydrolysis of trityl- or isobutyl-protected 4-amino-6-(substituted)pyridine-2-dialkylacetal of Formula E using a mineral acid in a polar solvent to obtain 4-amino-6-(substituted)picolinaldehyde of Formula F; (e) oxidation of 4-amino-6-(substituted)picolinaldehyde of Formula F using an alkali metal chlorite in the presence of an inorganic acid and a hypochlorous acid scavenger in an aqueous alcoholic solvent to obtain 4-amino-6-(substituted)picolinic acid of the Formula G; (f) esterification of 4-amino-6-(substituted)picolinic acid of Formula G with a compound of Formula R³Y; and (g) halogenating the 4-amino-6- (substituted) picolinate of Formula H with a halogen source to obtain 4-amino-3-halogen-6-(substituted)picolinate of Formula I. X, R, R¹, R² and R³, R⁴ are given in the claims. Invention relates to a process for producing 4-amino-3-halogen-6-(substituted)picolinate of Formula I, which includes the following steps: (a) to (d) above; (e) halogenation of 4-amino-6-(substituted)picolinaldehyde of Formula F with a halogen source to obtain 4-amino-3-halogen-6-(substituted)picolinaldehyde of Formula J; (f) oxidation of 4-amino-3-halogen-6-(substituted)picolinaldehyde of Formula J using an alkali metal chlorite in the presence of an inorganic acid and a hypochlorous acid scavenger in an aqueous alcoholic solvent to obtain 4-amino-3-halogen-6-(substituted)picolinic acid of Formula K; and (g) esterification of 4-amino-3-halogen-6- (substituted) picolinic acid of Formula K with a compound of Formula R³Y, to obtain 4-amino-3-halogen-6-(substituted) picolinate of Formula I. Invention also relates to compounds of Formula A, Formula C, Formula E and Formula F, where R, R¹, R², R⁴ are given in the claims.

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EFFECT: present methods enable to obtain 4-amino-5-fluoro-3-halogen-6-(substituted)picolinate and 4-amino-3-halogen-6-(substituted)picolinate from a non-pyridine source.

6 cl, 32 ex