Boron trifluoride etherate → HCID 21480715, compound

Participants

Reaction Conditions

Reaction Steps

To boron trifluoride etherate (0.413 mL, 3.36 mmol, 1.5 eq) cooled to -15° C. under nitrogen was added a solution of methyl 2-amino-7-chloro-9,10-dihydro-9,10-methano-9-anthracenecarboxylate (described in example 35c) (670 mg, 2.24 mmol) in methylene chloride (5 mL). This was followed by t-butyl nitrite (0.320 mL, 2.69 mmol, 1.2 eq) resulting in a precipitate and a dark blue-green solution color. After 10 min at -15° C., the reaction was warmed to 0° C. and stirred for additional 20 min The diazonium salt was precipitated by pentane dilution (100 mL). The precipitate was filtered and rinsed with cold diethyl ether to recover 650 mg of the crude salt. The diazonium salt was added to a solution of potassium carbonate (155 mg, 0.5 eq) in trifluoroacetic acid (5 mL) at 0° C. The reaction was brought to reflux for 20 h at which time the alkaline beta-naphthol test for diazonium salt was negative. Water (5 mL) was added to quench the reaction and the trifluoroacetic acid was removed in vacuo. The crude reaction mixture was diluted with 3N HCl (30 mL) and extracted with ethyl acetate (3×25 mL). Combined organic extracts were dried over anhydrous magnesium sulfate, filtered, and reduced to an oil. The reaction product was purified by flash chromatography over silica gel (35 mL, eluent; 10% ethyl acetate in hexane) to yield 540 mg (80%) of the title compound as a white solid. TLC analysis (Rf 0.21, 10% ethyl acetate in hexane). MS (CI, CH4) m/z 301 (M+1,100), 303 (42), 329 (M+29,10), 269 (31), 241 (56)

Provenance & Evidence