反应详情

The rac-trans-3,4-dihydro-3-hydroxy-2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran-6-carbonitrile used as the starting material was prepared as follows: (A) 3 g of 2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran-6-carbonitrile and 420 mg of sodium tungstate were heated in 30 ml of methanol and 30 ml of acetonitrile at 50° C. and 12 ml of 30% (w/v) hydrogen peroxide were added. After heating overnight the mixture was evaporated and the residue was taken up in dichloromethane and water. The organic phase was separated, dried over sodium sulphate and evaporated. The residue was chromatographed on silica gel using ethyl acetate/petroleum ether (1:3 and 1:2) for the elution to give 440 mg of la,7b-dihydro-2,2-dimethyl-7b-(2-pyridyl)-2H-oxireno[c][1]benzopyran-6-carbonitrile which was used without further purification. (B) 646 mg of la,7b-dihydro-2,2-dimethyl-7b-(2-pyridyl)-2H-oxireno[c][1]benzopyran-6-carbonitrile were dissolved in 100 ml of ethanol and 100 mg of 10% palladium-on-charcoal were added. The mixture was shaken under a hydrogen atmosphere overnight and then filtered. The filtrate was evaporated and the resulting oil was chromatographed twice on silica gel, with the elution being carried out initially using ethyl acetate/petroleum ether (1:3) and then 1% to 2% (v/v) methanol/dichloromethane. There were obtained 66 mg of rac-cis-3,4-dihydro-3-hydroxy-2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran-6-carbonitrile of melting point 186°-188° C. (from acetonitrile) and 340 mg of rac-trans-3,4-dihydro-3-hydroxy-2,2-dimethyl-4-(2-pyridyl)-2H-1-benzopyran-6carbonitrile of melting point 175°-176° C. (from t-butyl methyl ether).

1. customwas prepared
2. temperatureAfter heating overnight the mixture
3. customwas evaporated
4. customThe organic phase was separated
5. dry with materialdried over sodium sulphate
6. customevaporated
7. customThe residue was chromatographed on silica gel
8. washfor the elution