Tributylphosphine → {(S)-6-[(R)-4-bromo-5-cyano-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 (3.30 g) in tetrahydrofuran (5 mL) is added dropwise over 45 min to a solution of (S)-(6-hydroxy-2,3-dihydro-benzofuran-3-yl)-acetic acid methyl ester (for preparation see WO 2008001931; 2.10 g), (S)-4-bromo-1-hydroxy-indan-5-carbonitrile (2.40 g) and tri-n-butyl-phosphine (3.8 mL) in tetrahydrofuran (25 mL) at −10° C. The resulting solution is stirred for 30 min and then diluted with ethyl acetate. The resulting solution is washed with water and brine and dried (MgSO4). The solvent is evaporated and the residue is chromatographed on silica gel (cyclohexane/ethyl acetate 99:1→70:30) to give the title compound. LC (method 2): tR=1.15 min; Mass spectrum (ESI+): m/z=428/430 (Br) [M+H]+.

Provenance & Evidence