Water → 5-Chloro-6-isopropoxypyridin-3-OL

Participants

Reaction Steps

To a solution of 3-chloro-2-isopropoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (Preparation 34, 297.6 g, 897.9 mmol) in acetic acid:water (2.2 L:1.0 L) at 0° C. was added peracetic acid (191 mL; 1.077 mol) and the reaction was allowed to warm gradually to room temperature. After 4 hours the reaction was complete and was quenched with 0.5 M solution of sodium thiosulfate (225 mL). The resulting dark solution was evaporated to dryness and the residue was passed through a plug of silica (flushed with neat heptane gradually up to 10% EtOAc:heptane) to remove base line boronate salts. The filtrate evaporated to give a pale yellow viscous oil which contained 8% of the wrong regio-isomer. Further column chromatography was performed (SiO2 80 g/1.5 Kg using 30% EtOAc in heptane as eluent). Relevant fractions were evaporated to give a pale yellow solid which was triturated with heptane, dried under suction to give the title compound as a white solid.

Provenance & Evidence