1,1'-Carbonyldiimidazole → N-(4-iso-propylbenzenesulfonyl)-alpha-(4-tert-butyldimethylsilyloxymethyl-2-n-propylphenoxy)-3,4-methylenedioxyphenylacetamide

Participants

Reaction Steps

To a solution of 3.30 g (7.21 mmol) of the crude product from Step C dissolved in 40 mL of anhydrous THF was added 1.75 g (10.8 mmol) of 1,1'-carbonyldiimidazole and the reaction mixture was magnetically stirred and heated at reflux for 10 minutes. The reaction was then cooled to room temperature, 2.15 g (10.8 mmol) of 4-iso-propylbenzenesulfonamide and 1.61 mL (10.8 mmol) of 1,8-diazabicyclo[5.4.0]undec-7-ene were added and the reaction was stirred for an additional 30 minutes at room temperature. The mixture was then diluted with EtOAc (80 mL), washed with 10% aqueous citric acid, saturated aqueous NaCl, dried (MgSO4), filtered and evaporated. The residue was partially purified on a silica gel flash chromatography column eluted with CHCl3 --MeOH--NH4OH (92:8:0.5). The semi-purified material was combined and repurified on a second silica gel flash chromatography column eluted initially with 35% EtOAc-hexane, later with 50% EtOAc-hexane, and finally with 70% EtOAc-hexane. Combination of the purified fractions and evaporation afforded 3.20 g (69%) of the title compound as a yellow oil.

Provenance & Evidence