4-Hydroxythieno[2,3-b]pyridine-5-carbonitrile synthesis

Yield:63873-60-9 91%

Reaction Conditions:

in diphenylether; for 3 h;Heating / reflux;

Steps:

1

Diphenyl ether (250 mL) was heated to a gentle reflux using a heating mantle. Nitrogen was bubbled into the diphenyl ether as it was heating to reflux and then gently blown over the top of the solvent during the course of the reaction. Methyl 2-{[(1Z)-3-tert-butoxy-2-cyano-3-oxoprop-1-en-1-yl]amino}thiophene-3-carboxylate (14 g, 45 mmol) was added in portions over a few minutes. The reaction was heated to a gentle reflux for 3 hours then cooled to room temperature. Hexane (500 mL) was added and the resultant precipitate was filtered and washed extensively with hexane. The residual diphenyl ether was removed by stirring the solid for several hours in hexane followed by filtration to give 7.25 g of 4-hydroxythieno[2,3-b]pyridine-5-carbonitrile as a dark powder (91% yield), MS (ESI) m/z 174.9 (M+H).

References:

US2008/76926,2008,A1 Location in patent:Page/Page column 16