Lithium Hexamethyldisilazide → 1-(1,1-Dimethylethyl) 2-methyl (2R,5R)-2-[(2Z)-4-bromo-2-buten-1-yl]-5-(4-{[(2-fluorophenyl)methyl]oxy}phenyl)-1,2-pyrrolidinedicarboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of 1-(1,1-dimethylethyl) 2-methyl (2S,5R)-5-(4-{[(2-fluorophenyl)methyl]oxy}phenyl)-1,2-pyrrolidinedicarboxylate (D34, 0.2 g, 0.47 mmol) in dry THF (2 mL) at −78° C. was added LiHMDS (0.51 mL of a 1M solution in THF, 0.51 mmol). The mixture was allowed to warm to −30° C. and stirred for 30 min at this temperature. The yellow slurry was cooled to −78° C. and (2Z)-1,4-dibromo-2-butene (0.30 mL, 2.81 mmol) was added. The reaction mixture was left under stirring for 40 min and then quenched with a saturated ammonium chloride solution. The aqueous layer was extracted with ethyl acetate, dried (Na2SO4) and evaporated. The crude material was purified by chromatography on silica gel using cyclohexane/ethyl acetate (9:1) affording the title compound (101 mg, 38%); Rt (HPLC) 7.42 min. MS: (ES/+) m/z: 462 and 464 [MH+—Boc]; C28H33BrFNO5 requires 562.

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