反应详情

(2R)-(2,4-difluorophenyl)[(3R,6R)-3-(2,3-dihydro-1H-inden-2-yl)-6-isobutyl-2,5-dioxopiperazin-1-yl]ethanoic acid (example 22) (0.130 g) was stirred in anhydrous DMF (1 mL) and anhydrous potassium carbonate (0.020 g, 0.5 eq.) was added. The mixture was stirred at room temperature for 1 hour then cooled to −10° C. (ice-salt bath). The heterogeneous mixture was treated with 1-bromoethyl acetate (0.120 mL, excess) and stirred for 3.5 hours keeping the bath temperature between −10 and −5° C. It was then partitioned between DCM and 1M HCl aq. (20 mL each). The organic phase was separated (hydrophobic frit) and evaporated under reduced pressure to give a purple gum; this was purified by SPE cartridge (5 g, silica eluted with (i) cyclohexane×2, (ii) DCM×2, (iii) diethyl ether×2, (iv) ethyl acetate×2, (v) methanol×2 to give 1-(acetyloxy)ethyl (2R)-(2,4-difluorophenyl)[(3R,6R)-3-(2,3-dihydro-1H-inden-2-yl)-6-isobutyl-2,5-dioxopiperazin-1-yl]ethanoate (0.081 g) as a yellow foam.

1. stirringstirred for 3.5 hours
2. customthe bath temperature between −10 and −5° C
3. customIt was then partitioned between DCM and 1M HCl aq. (20 mL each)
4. customThe organic phase was separated (hydrophobic frit)
5. customevaporated under reduced pressure
6. customto give a purple gum
7. customthis was purified by SPE cartridge (5 g, silica
8. washeluted with (i) cyclohexane×2, (ii) DCM×2, (iii) diethyl ether×2, (iv) ethyl acetate×2, (v) methanol×2