反应详情

A mixture of the crude product of Example 33 containing 20% of its E isomer (9.2 g, 8.7 mmol) in 85% HCOOH (60 ml) was stirred for 1 hr at room temperature and evaporated in vacuo. The residue was treated with 90%-TFA (60 ml) for 1 hr at room temperature and poured into ice-water (300 ml). The insolubles were filtered off. The filtrate was chromatographed on a reverse phase column (Waters, prepPAK C18, 300 ml) and the column was eluted with 20% MeOH. The polar fractions were combined, concentrated in vacuo and the residue was triturated with isopropyl ether to give 1.15 g (33%) of the Z isomer and the less polar fractions gave 143 mg (4%) of the title compound.

1. customevaporated in vacuo
2. additionThe residue was treated with 90%-TFA (60 ml) for 1 hr at room temperature
3. additionpoured into ice-water (300 ml)
4. filtrationThe insolubles were filtered off
5. customThe filtrate was chromatographed on a reverse phase column (Waters, prepPAK C18, 300 ml)
6. washthe column was eluted with 20% MeOH
7. concentrationconcentrated in vacuo
8. customthe residue was triturated with isopropyl ether
9. customto give 1.15 g (33%) of the Z isomer