反应详情

2.00 g (5.24 mmol) of 3-benzyloxy-8-ethoxy-4,7-difluoro-6H-benzo[c]chromen-6-one, the compound of Example 841, were dissolved in 12 ml of THF, and 2.37 ml (23.0 mmol) of boron trifluoride/THF complex were added with ice-cooling. 24 ml of ethylene glycol dimethyl ether and then in portions 530 mg of sodium borohydride were subsequently added. The mixture was subsequently stirred at room temperature for 18 hours and then transferred onto ice. The mixture was subjected to conventional purification, giving 1.5 g (78% of theory) of 3-benzyloxy-8-ethoxy-4,7-difluoro-6H-benzo[c]chromene as colourless crystals. These were dissolved in THF, hydrogenated at a pressure of 1 bar in the presence of 0.6 g of Pd/C (5%), filtered and evaporated, giving 1.2 g (99% of theory) of 8-ethoxy-4,7-difluoro-3-hydroxy-6H-benzo[c]chromene as colourless crystals.

1. addition2.37 ml (23.0 mmol) of boron trifluoride/THF complex were added with ice-
2. temperaturecooling
3. customThe mixture was subjected to conventional purification