Water → 4-Chloro-5-hydroxypicolinic acid

By applying the reaction sequence of either esterification, Suzuki reaction, hydrogenation, saponification or esterification, Negishi reaction and saponification, a commercially available compound of Structure 32 may be transformed into a compound of Structure 33. The compounds of Structure 32 may be prepared, for instance, by reacting 4,5-dichloro-picolinic acid with water in their presence of an acid (Lit.: e.g. J. Prakt. Chem.; 27 (1883), 293) to give 4-chloro-5-hydroxy-picolinic acid. This compound may then be alkylated in analogy to literature procedures (T. Vermonden; D. Branowska; A. T. M. Marcelis; E. J. R. Sudholter; Tetrahedron 59 (2003), 5039-5045) to give 4-chloro-5-methoxy picolinic acid methyl ester which can be hydrolysed under acidic or basic conditions to the desired compound of Structure 32.

1. customthe reaction sequence of either esterification, Suzuki reaction, hydrogenation, saponification or esterification, Negishi reaction and saponification
2. customThe compounds of Structure 32 may be prepared, for instance

ORD-Eintrag

ord-ccde953a337e442aa257add66afcf1aa

Quelldatensatz

uspto-grants-2013_11

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08575200B2