Page 90 - Catalysts for Fine Chemical Synthesis Vol 1 - Robert & Poignant
P. 90

76             hydrolysis, oxidation and reduction

                  In a NMR tube, to a solution of the epoxy alcohol (2.5 mg) in CDCl 3 (0.5 mL)
               was added 4-dimethylaminopyridine (5 mg) and (R)-(‡)-a-methoxy-a-(trifluor-
               omethyl)phenylacetyl chloride (5 mg). The mixture was allowed to stand over-
               night at room temperature. The reaction was monitored by TLC to ensure
                                                        1
               complete consumption of the starting material. H and  19 F NMR spectra were
               carried out on the crude reaction mixture. In the  19 F NMR spectrum, each
               enantiomer gave a signal; an additional signal at ÿ71.8 ppm was ascribed to
                               19
               residual MTPA. ( F NMR (250 MHz, CDCl 3 ): d ÿ 70:7 (s, (2R,3R)-enantio-
               mer); ÿ72.0 (s, (2S,3S)-enantiomer) ).
                  1 H NMR (200 MHz, CDCl 3 ): d 7.37±7.27 (m, 5H, Ph); 4.06 (ddd, J 10.5 Hz, J
               4.9 Hz, J 3.0 Hz, CH±CH 2 ); 3.94 (d, J 3 Hz, 1H, CH±Ph); 3.81 (dd, J 12.5 Hz,
               J 4.9 Hz, 1H, CHaHb); 3.24 (m, 1H, CHaHb), 2.05 (br, 1H, OH).
                               ÿ1
                  IR (CHCl 3 , cm ): 3603, 3450 (O±H), 3060 (C±H epoxide), 3010 (C±H
               aromatic), 2927, 2875 (C±H aliphatic), 1606, 1461 (CˆC), 1390, 1308, 1289,
               1203 (C±OH, C±O±C), 1103, 1079, 1023, 882, 861, 838.
                  Mass: calculated for C 9 H 10 O 2 : m/z 150.06808; found [M] ‡8  150.06781.


               5.2.2  EPOXIDATION OF (E)-2-METHYL-3-PHENYL-2-PROPENOL          [4]



                                         Ti(O-iPr) 4 , (+)-DIPT  O
                       Ph           OH                     Ph          OH
                                          t-BuOOH, CH 2 Cl 2
                              Me                                 Me
                                                                ( 2S,3S)


               Materials and equipment
               . l-(‡)-Diisopropyl tartrate ( (‡)-DIPT), 350 mg, 1.5 mmol, 0.075 eq
                                                        Ê
               . Dichloromethane stored over preactivated 3 A molecular sieves, 50 mL
                                     Ê
               . Activated powdered 4 A molecular sieves, 1.2 g
               . Titanium isopropoxide, 297 mL, 1 mmol, 0.05 eq
               . Anhydrous solution of 5.5 M of tert-butyl hydroperoxide in isooctane stored
                  over molecular sieves, 7.2 mL, 40 mmol, 2 eq
               . (E)-2-Methyl-3-phenyl-2-propenol, 3 g, 2.9 mL, 20 mmol
               . Aqueous solution of sodium hydroxide (30 %) saturated with sodium chlor-
                  ide, 6 mL
               . Celite 1
               . Brine
               . Sodium sulfate
               . Silica gel 60 (0.063±0.04 mm)
               . Dichloromethane, diethyl ether, petroleum ether, methanol
               . p-Anisaldehyde
   85   86   87   88   89   90   91   92   93   94   95