Reaction Steps
[step 1] Under ice-cooling, sodium hydride (1.9 g, 47.13 mmol) was suspended in DMF (20 mL), a solution of diethyl cyanomethylsulfonate (9.2 mL, 56.55 mmol) in DMF (20 mL) was gradually added dropwise, and the mixture was stirred at room temperature for 1 hr. To the mixture was added a solution of 8-bromo-6,11-dihydrodibenzo[b,e]oxepin-11-one (WO9015599; 11 g, 37.70 mmol) in DMF (80 mL), and the mixture was stirred at room temperature for 2 hr. To the mixture was added water (80 mL), and the mixture was stirred at room temperature for 30 min. The precipitated solid was collected by filtration to give (E)-2-(8-bromo-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile and (Z)-2-(8-bromo-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile as a mixture (11.48 g, 97%, E/Z=3/1). [step 2] A mixture (11.48 g, 36.78 mmol) of (E)-2-(8-bromo-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile and (Z)-2-(8-bromo-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile obtained in step 1, palladium acetate (0.31 g, 1.84 mmol), 1,3-bisdiphenylphosphinopropane (0.76 g, 1.84 mmol) and cesium carbonate (17.98 g, 55.17 mmol) were suspended in ethanol (57 mL) and DMF (57 mL), and the mixture was stirred under a carbon monoxide atmosphere at 70° C. for 1.5 hr. To the mixture was added 2 mol/L aqueous sodium hydroxide solution (25 mL), and the mixture was stirred at 70° C. for 3 hr. Under ice-cooling, the mixture was adjusted to pH=3 with 2 mol/L hydrochloric acid, and extracted with ethyl acetate. The organic layer was washed with water and brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue (8.2 g, 29.39 mmol) was dissolved in THF (50 mL), borane-THF 1 mol/L solution (44 mL, 44.09 mmol) was added under ice-cooling, and the mixture was stirred at room temperature for 4 hr. To the mixture were added ethyl acetate (100 mL) and water (50 mL), and the mixture was stirred at 50° C. for 1.5 hr, and extracted with ethyl acetate. The organic layer was washed with 1 mol/L hydrochloric acid, saturated aqueous sodium hydrogen carbonate solution and brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (hexane/ethyl acetate=90/10 to 60/40) to give (E)-2-(8-hydroxymethyl-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile (2.65 g, 34%) and (Z)-2-(8-hydroxymethyl-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile (962 mg, 12%). [step 3] (E)-2-(8-Hydroxymethyl-6,11-dihydrodibenzo[b,e]oxepin-11-ylidene)acetonitrile (3.5 g, 13.3 mmol) obtained in step 2 was dissolved in THF (133 mL), 2,6-lutidine (9.3 mL, 79.8 mmol), lithium bromide (6.9 g, 79.8 mmol) and methanesulfonic anhydride (5.8 g, 33.3 mmol) were added, and the mixture was stirred at room temperature for 5 hr. To the mixture was added water (50 mL), and the mixture was extracted with ethyl acetate (200 mL). The organic layer was washed with 1 mol/L hydrochloric acid (300 mL), saturated aqueous sodium hydrogen carbonate solution (200 mL) and brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. To the residue was added silica gel and the mixture was suction filtered, and the filtrate was concentrated under reduced pressure to give the title compound (3.63 g, 84%).
