Cesium carbonate → Methyl O-(3'-amino-1,1'-biphenyl-3-yl)-N-triphenylmethyl-L-serinate

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Reaction Steps

Triphenyl arsine (0.31 g, 1.0 mmol, 0.1 equiv) and dichloro-bis(triphenylphosphine)-palladium(II) (0.35 g, 0.50 mmol, 0.05 equiv) were stirred under an argon atmosphere in DME (dimethoxy ethane; 56 mL) at rt for 30 min. Methyl O-(3-bromophenyl)-N-triphenylmethyl-L-serinate (Example 1) (5.16 g, 10.0 mmol, 1.0 equiv) and 3-amino phenyl boronic acid hemisulfate (2.2 g, 6.0 mmol, 1.2 equiv) were added as solids, followed by a 2M aqueous solution of cesium carbonate (15.0 mL, 30.0 mmol, 3 equiv). The reaction mixture was stirred for 3 h at rt and partioned between toluene and water. The organic layer was separated and dried over sodium sulfate. After filtration and evaporation of the solvents in vacuuo the crude product was purified by chromatography on SiO2 (gradient: toluene to toluene/-ethanol 97:3) Yield: 7.3 g, 39.0%. 1H NMR (CDCl3, 200 MHz) δ 7.65-7.40 (m, 10H); 7.25-7.12 (m, 11H); 6.97 (d, 2H); 4.70 (dd, 1H); 4.7 (dd, 1H); 3.75-3.65 (m, 3H); 3.24 (s, 3H); 2.90 (d, 1H). MS (DCI/NH3) 546 (M+NH4+), 529 (M+H); 234 (CPh3).

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