Benzyl 2-[3-(4-cyanophenoxy)-3-methyl-1-butyn-1-yl]pyridine-5-carboxylate → benzyl 6-(6-cyano-2,2-dimethyl-2H-1-benzopyran-4-yl)-3-pyridinecarboxylate

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Reaktionsschritte

9 g of benzyl 2-[3-(4-cyanophenoxy)-3-methyl-1-butyn-1-yl]pyridine-5-carboxylate were dissolved in 300 ml of 1,2-dichlorobenzene and the solution was added dropwise over a period of 5 hours to 100 ml of 1,2-dichlorobenzene heated at reflux. After a further 2 hours the mixture was allowed to cool to room temperature and was then evaporated. The residue was chromatographed on silica gel using ethyl acetate/petroleum ether (1:9), (1:6) and (1:4) for the elution. There were obtained 5.5 g of benzyl 6-(6 -cyano-2,2-dimethyl-2H-1-benzopyran-4-yl)-3-pyridinecarboxylate which was used without further purification.

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