Tributylphosphine → {(S)-6-[(R)-4-bromo-7-fluoro-indan-1-yloxy]-2,3-dihydro-benzofuran-3-yl}-acetic acid methyl ester

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Reaction Steps

A solution of di-tert.-butyl azodicarboxylate (18 g) in tetrahydrofuran (80 mL) is added dropwise over 45 minutes to a solution of (S)-methyl 2-(6-hydroxy-2,3-dihydrobenzofuran-3-yl)acetate (11 g), (S)-4-bromo-7-fluoro-2,3-dihydro-1H-inden-1-ol (11.95 g) and tributylphosphine (19.3 mL) in tetrahydrofuran (320 mL) at −10° C. The resulting solution is stirred for 30 minutes and then partitioned between saturated aqueous NaHCO3 solution and dichloromethane. The aqueous phase is extracted with dichloromethane. The combined organic phases are dried (MgSO4) and concentrated. The residue is chromatographed on silica gel (cyclohexane/ethyl acetate 90:10→70:30) to give the title compound. Yield: 10.35 g; LC (method 1): tR=1.41 min; Mass spectrum (ESI+): m/z=421 [M+H]+.

Provenance & Evidence