Cesium carbonate → (2S,5S)-2-(2-(9-((2S,5S)-1-(tert-butoxycarbonyl)-5-methylpyrrolidine-2-carbonyloxy)-8-oxo-8,9,10,11-tetrahydro-5H-dibenzo[c,g]chromen-3-yl)-2-oxoethyl) 1-tert-butyl 5-methylpyrrolidine-1,2-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

(2S,5S)-2-(2-(9-bromo-8-oxo-8,9,10,11-tetrahydro-5H-dibenzo[c,g]chromen-3-yl)-2-oxoethyl) 1-tert-butyl 5-methylpyrrolidine-1,2-dicarboxylate (700 mg, 1.17 mmol) was treated with a solution of (2S,5S)-1-(tert-butoxycarbonyl)-5-methylpyrrolidine-2-carboxylic acid (375 mg, 1.64 mmol) in acetone (6 mL) and Cs2CO3 (267 mg, 0.82 mmol). The stirred reaction mixture was heated to 40° C. for 16 h, then cooled to RT and diluted with CH2Cl2 and extracted 3×. The organic phase was washed with brine, then dried over MgSO4, filtered and concentrated under reduced pressure. The crude residue was purified by silica column chromatography (40% to 100% EtOAc/hexanes) to afford (2S,5S)-2-(2-(9-((2S,5S)-1-(tert-butoxycarbonyl)-5-methylpyrrolidine-2-carbonyloxy)-8-oxo-8,9,10,11-tetrahydro-5H-dibenzo[c,g]chromen-3-yl)-2-oxoethyl) 1-tert-butyl 5-methylpyrrolidine-1,2-dicarboxylate (464 mg, 53%).

Provenance & Evidence