Triethylamine → 12-[4-deoxy-2-O-benzyl-3-methyl-beta-D-allopyranosyl]-2,3,9,10-tetrafluoro-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione

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Reaction Steps

To a solution of this material ( ) in 5 mL of dry THF, at −78° C. under Ar, was added MeMgBr (1.4M solution in THF-toluene, 0.49 mL, 0.69 mmol) dropwise. The resulting mixture was stirred at −78 C. for 2 h and then it was allowed to warm to −20° C. over 2 h. The mixture was then quenched with 1 mL of 1 M NaHCO3, and then it was patitioned with ethyl acetate (20 mL) and 1 M NaHCO3 (5 mL). The organic phase was separated, washed (H2O brine), dried (MgSO4) and evaporated. Flash chromatography (SiO2/2-28% ethyl acetate-hexane) of the residue afforded 12-[4-deoxy -6-O-(tert-butyldiphenylsilyl)-2-O-benzyl-3-methyl-β-D-allopyranosyl]-2,3,9,10-tetrafluoro-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (0.052 g, 43%) and then 12-[4-deoxy-6-O-(tert-butyldiphenylsilyl)-2-O-benzyl-3-methyl-β-D-glucopyranosyl]-2,3,9,10-tetrafluoro-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (0.028 g, 23%); MS (ESI−) m/e 884 (M−H)−. To a cold (5° C.) solution of 12-[4-deoxy-6-O-(tert-butyldiphenylsilyl)-2-O-benzyl-3-methyl -β-D-allopyranosyl]-2,3,9,10-tetrafluoro-12,13-dihydro-5H-indolo[2,3-a]pyrrolo [3,4-c]carbazole-5,7(6H)-dione (0.050 g, 0.056 mmol) in 5 mL of MeCN under Ar was added Et3N.3HF (0.091 mL, 0.56 mmol) and the mixture was stirred at room temperature for 2 days. The resulting mixture was diluted with ethyl acetate, washed (1M NaHCO3, H2O, brine) dried (MgSO4) and evaporated. The residue was purified by prep tlc (SiO2/ethyl acetate-hexane, 3:2) to give 12-[4-deoxy-2-O-benzyl-3-methyl-β-D-allopyranosyl]-2,3,9,10-tetrafluoro-12,13-dihydro-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (0.026 g, 72%) as a yellow solid; MS (ESI−) m/e 646 (M−H)−.

Provenance & Evidence