Methanol → HCID 178464043, compound

Participants

Reaction Conditions

Reaction Steps

A 25° C. solution of 0.25 g (0.49 mmol) of [2-[[2-[2-(diethylamino)ethyl]-8-methoxy-2H-[1]benzothiopyrano[4,3,2-cd]indazol-5-yl]amino]ethyl]-carbamic acid; 1,1-dimethylethyl ester (6) in 7.5 mL of dichloroethane was treated dropwise with 2.45 mL (2.45 mmol) of a 1M solution of boron tribromide in dichloromethane. The mixture was stirred at 25° C. for 18 hr, treated cautiously with 3 mL of methanol, then heated at reflux for 6 hr. After cooling to 25° C., the precipitated solids were collected by filtration, washed successively with methanol and dichloromethane, and dried at 200 mm/60° C./overnight to give 0.3 g of 4, 95.2% pure by HPLC. The solids were dissolved in 10.6 mL of ethanol:H2O (4:1) and the solution was treated portionwise with 1.6 mL of a 2.6M solution of hydrogen bromide in 2-propanol. After standing overnight at 0°-5° C., the precipitated solids were collected by filtration, washed, and dried as above to give 0.28 g (90%) of 4 as a salt with 2.9 equivalents of hydrogen bromide, mp 282° C. (dec), 96.1% pure by HPLC.

Provenance & Evidence