| 摘要 |
Preparation of pyridine-2,3-dicarboxylic acid esters of formula (I) comprises reacting a 2,3-dichloropyridine compound of formula (II) with carbon monoxide and an alcohol of formula R-OH (III), in the presence of a base (B) and catalytically active complex of palladium and a diphosphine of formula R4R5P-Q-PR6R7 (IV). (B) is (a) an alkali or alkaline earth metal salt of a lower carboxylic acid, hydrogen carbonate or (di)hydrogen phosphate; or any other base with a pKa of 4 - 9 (preferably sodium or potassium acetate). R = 1-6C alkyl, 3-6C cycloalkyl, aryl or arylalkyl; R1-R3 = H, optionally fluorinated 1-6C alkyl, (1-6C alkoxy)(1-6C)alkyl or (1-6C alkoxy)carbonyl; R4-R7 = 1-6C alkyl, optionally substituted phenyl or 3-6C cycloalkyl; Q = 1,1'-ferrocene-diyl or (CH2)n; n = 3 or 4. 2,3-dichloro-5-(methoxymethyl)pyridine (IIa) is new. |
