1,2-Dimethoxyethane → [5-(5-Ethyl-6-methoxy-2-methyl-pyridin-3-yl)-thiophen-2-ylmethyl]-carbamic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To a nitrogen flushed mixture of 3-ethyl-2-methoxy-6-methyl-5-(4,4,5,5-tetramethyl-[1,3,2-dioxaborolan-2-yl)pyridine (1.0 g, 3.6 mmol), cesium carbonate (3.52 g, 11 mmol), and (5-bromo-thiophen-2-ylmethyl)-carbamic acid tert-butyl ester (1.2 g, 4.0 mmol) in 1,2-dimethoxyethane (20 mL) and water (4 mL) is added palladium tetrakis(triphenylphosphine) (290 mg, 0.25 mmol) and the reaction mixture is heated to about 110° C. After maintaining the reaction mixture at 110° C. for 12 hr, the mixture is cooled, poured into ethyl acetate (50 mL) and washed with water and brine, dried over sodium sulfate, filtered and concentrated. The residue is chromatographed on SiO2, eluting with heptane-30% ethyl acetate to afford 0.98 g of [5-(5-ethyl-6-methoxy-2-methyl-pyridin-3-yl)-thiophen-2-ylmethyl]-carbamic acid tert-butyl ester. A solution of this ester in MeOH is then treated with saturated HCl in EtOAc (50 mL) and heated to about 75° C. After 6 hr at 75° C., the mixture is concentrated, and triturated with acetonitrile/water to afford 2.8 g of 5-(5-aminomethylthiophen-2-yl)-3-ethyl-6-methyl-1H-pyridin-2-one hydrochloride as a white solid (78% yield). LC/MS: RT 1.77 min; m/e 249 (M+H).

Provenance & Evidence