After 3h of reaction was isolated in 82% yield (109 mg) and 92% ee With (S)-SYNPHOS: After 5h of reaction, a 97/3 mixture of adducts 2j/2j' was isolated in 70% yield (92 mg) and -54% ee With (R)-DIFLUORPHOS: After 6h of reaction, a 95/5 mixture of adducts 2j/2j' was isolated in 66% yield (87 mg) and 80% ee. 1,6-asymmetric conjugate addition on dienone (1h): Typical Procedure A flame dried Schlenk flask, under an argon atmosphere, was charged with diphosphine ligand mmol, 5 mol%) and dry THF (1 mL). The resulting mixture was stirred for 10 min, 1M solution of diethylzinc in hexanes (1.5 mL, 1.5 mmol, 3 equiv.) was added and the reaction mixture was stirred for 10 min. Finally, a solution of substrate 1h ,
The reaction mixture was stirred at room temperature until the completion. The reaction was quenched by the addition of solid NH4Cl (500 mg) The solution was stirred for 1 h and then filtered on a small pad of silica, washed with EtOAc, and concentrated under vacuo. The residue was dissolved in 4 mL of dry CH2Cl2 and DBU (100 mL, 0.7 mmol, 1.4 equiv) was added to the solution. The reaction was stirred for 5 h and then filtered on a small pad of silica, washed with EtOAc, and concentrated under vacuo. The crude product was purified by flash chromatography on silica gel (pentane/Et2O: 85/15) to afford 2k. Data were in accordance with literature. 13b Ee was obtained by GC analysis of the purified product (Beta-dex column, helium (40 cm/sec, 100?C100?C, pp.1-2 ,
After 5 h of reaction, 2k was isolated in 60% yield (63 mg) and 82% ee With (S)-SYNPHOS: After 14 h of reaction, 2k was isolated in 54% yield (56 mg) and -82% ee. With (R)-DIFLUORPHOS: After 14 h of reaction, pp.2-14 ,
186; For an excellent comprehensive review, see also: (b) Hawner, C.; Alexakis, A, Comprehensive Organic Synthesis II Chem. Commun, vol.4, pp.46-7295, 2010. ,
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(15) For instance, it was observed that the Cu/phosphoramidite catalysed addition of Et2Zn or Et3Al to a cyclic dienone structurally close to 1h gave the 1,6-adduct, whereas the Cu, J. Am. Chem. Soc, issue.14, pp.94-5386, 1972. ,
For industrial enantioselective metal-catalytic processes using BINAP, see: (b) Akutagawa, S, Acc. Chem. Res. Appl. Catal. A: General, vol.23, issue.128, pp.345-171, 1990. ,
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