Ammonium Chloride → 4-Chloro-2-[2-(dimethylamino)pyridin-4-yl]phenol

Participants

Reaction Conditions

Reaction Steps

A mixture of 2-chloro-4-(5-chloro-2-methoxyphenyl)pyridine (Preparation 866, 157 mg, 0.618 mmol), azetidine hydrochloride (120 mg, 1.2 mmol), and N,N-diisopropylethylamine (220 uL, 1.2 mmol) in N,N-dimethylacetamide (4.1 mL, 44 mmol) was heated 20 minutes at 170° C. under microwave irradiation. The reaction mixture was poured into water and saturated aqueous ammonium chloride and extracted with ethyl acetate (3×). The combined organic layers were washed with water then brine, dried over sodium sulfate, filtered and concentrated in vacuo. The residue was taken up in methylene chloride, concentrated onto diatomaceous earth, and purified by automated flash chromatography (12 g SiO2, hexanes to 9:1 ethyl acetate-methanol). A single peak containing the major products eluted from the column. The appropriate fractions were concentrated in vacuo. The residue was dissolved in 1 mL of dimethylsulfoxide, filtered through a plug of cotton, and purified by reverse-phase HPLC to afford 4-chloro-2-[2-(dimethylamino)pyridin-4-yl]phenol as a tan solid (50 mg, 33%) followed by 4-chloro-2-(2-chloropyridin-4-yl)phenol as a light pink solid (24 mg, 16%). Unexpectedly 4-chloro-2-[2-(dimethylamino)pyridin-4-yl]phenol was isolated as the main product and none of the intended product was isolated. This presumably occurred due to decomposition of the dimethylacetamide to provide dimethylamine which reacted preferentially to give 4-chloro-2-[2-(dimethylamino)pyridin-4-yl]phenol

Provenance & Evidence