Cyclobutanol → (S)-cyclobutyl 4-acetyl-7-bromo-3-methyl-3,4-dihydroquinoxaline-1(2H)-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of cyclobutanol (28.8 g, 399 mmol), 1,2-dichloroethane (450 mL), triphosgene (22.1 g, 74.41 mmol) and N,N-diisopropylethyl amine (58.0 mL, 333 mmol) was stirred at 50° C. for 2 hr. A solution of (S)-1-(6-bromo-2-methyl-3,4-dihydroquinoxaline-1(2H)-yl)ethan-1-one (10.0 g, 37.2 mmol) and N,N-diisopropylethyl amine (58.0 mL, 333 mmol) in 1,2-dichloroethane (180 mL) was added dropwise. The resulting solution was stirred for 5 h at 50° C. After cooling to room temperature, the reaction mixture was concentrated under vacuum. The residue was purified via column chromatography on silica gel (eluting with 25% ethyl acetate-petroleum ether) to afford cyclobutyl (S)-4-acetyl-7-bromo-3-methyl-3,4-dihydroquinoxaline-1(2H)-carboxylate (20 g, 73%) as yellow oil. MS (ESI, pos. ion) m/z 367, 369 [M+1]+.

Provenance & Evidence