1,2-Dichloroethane → (+/-)-trans-3-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-4-[(S)-(-)-3-acetylthio-2-methylpropionyloxy]-2H-1-benzopyran

Beteiligte Stoffe

Reaktionsschritte

To a mixture of 94 g of (±)-trans-3-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-4-hydroxy-2H-1-benzopyran, 800 ml of ethylene chloride and 32.4 ml of pyridine was added 66 g of (S)-(-)-3-acetylthio-2-methylpropionyl chloride under ice-cooling over 5 minutes and stirred for 1.5 hours under room temperature. The reaction mixture was washed with diluted hydrochloric acid once and 10% aqueous sodium chloride solution twice. The organic layer was separated, dried over magnesium sulfate and concentrated under reduced pressure to give 139.8 g of (±)-trans-3-bromo-6-cyano-3,4-dihydro-2,2-dimethyl-4-[(S)-(-)-3-acetylthio-2-methylpropionyloxy]-2H-1-benzopyran as a light yellow oily substance.

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