Bromine → 2-(1-(4-Bromophenyl)-3-(1,3-dioxan-2-yl)-1-oxopropan-2-yl) 1-tert-butyl pyrrolidine-1,2-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

Bromine (1.3 mL, 25.2 mmol) was added to a solution of Example J2, 1-(4-bromophenyl)-3-(1,3-dioxan-2-yl)propan-1-one (7.7 g, 25.7 mmol) in diethyl ether (60 mL) and 1,4-dioxane (40 mL) and the solution stirred 30 min at 24° C. (Until TLC indicated reaction complete). The solvent was removed by rotory evaporation and the residue was taken up in acetonitrile (350 mL). (S)—N-Boc-Proline (5.54 g, 25.7 mmol) was added followed by dropwise addition of Hunig's base (8.5 mL, 51.5 mmol) and the reaction was stirred 6 hours before being concentrated. The crude product was taken up in CH2Cl2 and charged to a 40 (M) Biotage silica gel cartridge. Gradient elution 15-100% B over 1 L (A=hexanes; B=ethyl acetate) gave Example J3, 2-(1-(4-bromophenyl)-3-(1,3-dioxan-2-yl)-1-oxopropan-2-yl) 1-tert-butyl pyrrolidine-1,2-dicarboxylate 13 g (100%).). RT=2 2 minutes (condition 1); LCMS: Anal. C23H30BrNO7 Calcd. 534; found: 534 (M+Na)+.

Provenance & Evidence