反应详情

A mixture of 10.9 g of 2,3-diaminopyridine (IIa) and 20.6 g of 2-methoxy-4-propargyloxybenzoic acid (m.p.142°; obtainable by the reaction of methyl 2,4-dihydroxybenzoate with propargyl chloride to give methyl 2-hydroxy-4-propargyloxybenzoate (m.p. 100°); reaction of this with methyl iodide to give methyl 2-methoxy-4-propargyloxybenzoate (m.p. 88°) and hydrolysis) is added in portions with stirring to 500 ml of POCl3. The mixture is boiled for 4 hours, concentrated, and the residue is treated with 375 ml of 10% hydrochloric acid. The precipitated 2-(2-methoxy-4-propargyloxyphenyl)imidazo(4,5-b)pyridine hydrochloride ("M") is filtered off. M.p. 247° (from methanol).