Diisopropylethylamine → (2S,4S)-1-tert-butyl 2-(3-chloro-8-oxo-8,9,10,11-tetrahydro-5H-dibenzo[c,g]chromen-9-yl) 4-ethoxypyrrolidine-1,2-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

To a slurry of 9-bromo-3-chloro-10,11-dihydro-5H-dibenzo[c,g]chromen-8(9H)-one (2.50 g, 6.8 mmol) in MeCN (20 mL) was added (2S,4S)-1-(tert-butoxycarbonyl)-4-ethoxypyrrolidine-2-carboxylic acid (2.68 g, 10.3 mmol) and DIPEA (1.3 mL, 7.5 mmol). The reaction was heated with stirring to 50° C. for 18 h. The reaction was then cooled to room temperature and diluted with EtOAc. The solution was washed with HCl (1N) and brine. The aqueous layers were back extracted with EtOAc and the resulting organic layers were combined, dried (Na2SO4) and concentrated under reduced pressure. The crude residue was purified by silica column chromatography (15% to 50% EtOAc/Hexanes) to afford (2S,4S)-1-tert-butyl 2-(3-chloro-8-oxo-8,9,10,11-tetrahydro-5H-dibenzo[c,g]chromen-9-yl) 4-ethoxypyrrolidine-1,2-dicarboxylate (2.08 g, 56%).

Provenance & Evidence