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With (S)-3,3'-bis-(2,4,4-tricyclohexylphenyl)-[1,1']-binaphthalenyl-2,2'-dioxaphosphoric acid; sodium carbonate; Selectfluor; In toluene; at 20℃; for 48h; |
General procedure: To the substrate 1 (0.25 mmol) in a 1 dram (15 x 45 mm) vial equipped with an 8 mm magnetic stirrer bar was added toluene (1.25 ml). Subsequently, anhydrous Na2C03(39.8 mg, 0.375 mmol), Selectfluor (132 mg, 0.375 mmol) and (S)-TCYP (12.4 mg, 0.0125 mmol) were added. The vial was capped with a screw cap and stirred rapidly for the specified time at room temperature, the vial standing on the stirrer plate. After this time, the reaction was diluted with ethyl acetate and poured into satd. NaHC03solution. After extraction, the aqueous layer was extracted with further EtOAc and the combined organics were, dried (Na2S04) and evaporated in vacuo. The crude residue was purified by flash column chromatography. It is notable that fast and efficient stirring should be maintained in order to achieve reliable results.Reaction carried out according to general procedure using 5,6,7,8-Tetrahydro-2- naphthol (37.0 mg, 0.25 mmol) for 40h. Purification by column chromatography, eluting with a gradient of 50 to 80 % CH2CI2in Hexane gave 2a as a colourless oil (17 mg, 0.102 mmol, 41%). Also isolated was a mixture of 2b and 2c as a colourless oil (10 mg, 0.060 mmol, 24%) and 2d as a yellow solid (5 mg, 1 1%).2a: 1H NMR (400 MHz, CDC13) delta 6.82 (dd, J= 10.1 , 6.3 Hz, 1H), 6.21 (dt, J = 10.1 , 1.6 Hz, 1H), 6.06 (s, 1H), 2.63 (tdd, J= 13.3, 5.1 , 1.6 Hz, 1H), 2.43 (d, J= 13.1 Hz, 1H), 2.32 (dddt, J= 14.0, 8.0, 3.9, 2.2 Hz, 1H), 2.05 (dtq, J= 13.8, 4.9, 2.4 Hz, 1H), 1.88 (tt, J= 13.5, 3.9 Hz, 1H), 1.81 - 1.69 (m, 1H), 1.57 - 1.33 (m, 2H).19F NMR (376 MHz, CDC13) delta -155.92 (dt, J= 38.6, 6.7 Hz).13C NMR (151 MHz, CDC13) delta 185.63 (d, J= 4.8 Hz), 158.83 (d, J= 18.7 Hz), 145.94 (d, J= 21.8 Hz), 129.31 (d, J= 7.8 Hz), 123.95 (d, J= 4.7 Hz), 87.43 (d, J= 164.8 Hz), 38.27 (d, J= 25.7 Hz), 32.02 (s), 27.38 (s), 20.50 (d, J= 1.3 Hz), m/z HRMS (EI) found [M]+166.0793, CioHnOiFi requires 166.0794. [a]D20= - 60.6 (c 1.0, CHCI3). HPLC (Chiralpak IC column, 99:01 hexanes/isopropanol, 1 ml/min); tr= 18.1 min (minor), 24.8 min (major); 63% ee. |