反应详情

Approximately 30 ml of methanol and 2.88 g of O-methylhydroxyl-amino hydrochloride were added to the second half of the dimethyl sulfoxide solution of Example 1. The mixture was stirred for a further 12 hours at room temperature, and the batch was worked up as described for Example 1. The dried methyl tert-butyl ether phase was filtered through silica gel. After evaporation of the residue on a rotary evaporator, there remained 3.2 g of crude product. To concentrate the desired E isomer, the crude product was taken up in 50 ml of saturated methanolic hydrochloric acid, and the mixture was stirred for 3 hours at room temperature. For working-up, the mixture was treated with methyl tert-butyl ether. The organic phase was washed with sodium chloride solution until neutral, dried over sodium sulfate and concentrated. Some of the remaining oil crystallized. After trituration with diisopropyl ether, 1.05 g of the title compound were obtained as colorless solid.

1. filtrationThe dried methyl tert-butyl ether phase was filtered through silica gel
2. customAfter evaporation of the residue
3. customon a rotary evaporator, there
4. concentrationTo concentrate the desired E isomer
5. stirringthe mixture was stirred for 3 hours at room temperature
6. additionthe mixture was treated with methyl tert-butyl ether
7. washThe organic phase was washed with sodium chloride solution until neutral,
8. dry with materialdried over sodium sulfate
9. concentrationconcentrated
10. customSome of the remaining oil crystallized