Ruthenium → Ruthenium

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A ruthenium chiral complex was prepared as follows: (1S, 2S)-(+)—N-p-Tosyl-1,2-diphenylethylenediamine (1.10 g, 3.0 mmol, Aldrich) and [RuCl2(η6-para-cymene)]2 (0.92 g, 1.5 mmol, STREM) were dissolved in 35 ml of i-PrOH and stirred at 80° C. for 1 h. The reaction was concentrated under reduced pressure to ˜5 ml. The mixture was cooled to −20° C., and 10 mL of H2O was added with shaking. The solution was scratched with a spatula until it all solidifies. The solid was filtered and washed with H2O to provide the desired chiral complex. The complex was dried in vacuo. A 5/2 mixture of formic acid and Et3N was prepared as follows: A mixture of formic acid (190 ml, 232 g, 5.03 mmol) and Et3N (280 mL, 203 g, 2.01 mmol) were heated to 100° C. under reduced pressure (˜100 mm Hg) to remove volatile chemicals. The residue was used without further purification. 7-Cyanochroman-4-one (10.2 g, 58.9 mmol) and a 5/2 mixture of formic acid and Et3N (50 mL) were dissolved in CH3CN (120 ml). The ruthenium chiral complex (S, S—, 0.380 g, 0.589 mmol) was added. The reaction was stirred at RT for 14 h. After the addition of H2O (100 mL), the mixture was extracted with EtOAc (300 ml, 3×). The organic phases were combined and washed sequentially with a saturated NaHCO3 solution and brine. The organic solution was dried over MgSO4, filtered and concentrated in vacuo to provide a crude brown solid which was purified by flash column chromatography (silica, 50% EtOAc in hexane) to provide the title compound.

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