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Supplementary data
Molybdenum(0) and Tungsten(0) Catalysts with Enhanced Reactivity for Allylic Substitution: Regioselectivity and Solvent Effects
Andrei V. Malkov,a,b Ian R. Baxendale,b Darren J. Mansfield,c and Pavel Kočovský*,a,b
a Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
bDepartment of Chemistry, University of Leicester, Leicester LE1 7RH, U.K.
cAventis CropScience UK Ltd, Chesterford Park, Saffron Walden, Essex, CB10 1XL, U.K.
(E)-1-Acetoxy-1-phenyl-but-2-ene. To a stirred solution of crotonaldehyde (3.50 g; 50 mmol) in THF (50 mL) at -78 C was added phenyl lithium (27.8 mL; 50 mmol; 1.8 M in THF). The mixture was maintained at -78 C for 1 h and then allowed to warm to room temperature. The reaction was quenched by pouring into saturated aqueous ammonium chloride (30 mL) and extracted with ether (340 mL), dried (MgSO4) and the solvent removed under reduced pressure. The crude product was dissolved in dichloromethane (50 mL) and triethylamine (9.107 g; 90 mmol), acetic anhydride (7.15 g; 70 mmol), and DMAP (200 mg; 1.7 mmol) were added, and the mixture was then stirred at room temperature for 3 h. The solution was washed with 10% hydrochloric acid (2 30 mL), saturated aqueous sodium hydrogen carbonate (2 30 mL), and dried (MgSO4). Removal of the solvent under reduced pressure and purification by column chromatography on silica (68 g; petroleum ether/ether 14:1) gave the title product (6.46 g; 68%) as a pale yellow oil: 1H NMR 7.35-7.20 (5 H, m, arom), 6.21 (1 H, d, J = 5.7 Hz), 5.70 (2 H, m), 2.06 (3 H, s, COMe), 1.71 (3 H, d, J = 5.7 Hz, Me); 13C NMR 169.7 (C), 139.6 (C), 129. 5 (CH), 129.3 (CH), 128.3 (2 CH), 127.7 (CH), 126.7 (2 CH), 76.1 (CH), 21.1 (CH3), 17. 5 (CH3), in accordance with the literature.[1]
(E)-2-Acetoxy-4-phenyl-but-3-ene 4. To a solution of (E)-4-phenyl-3-buten-2-one (29.2 g; 199.7 mmol) and cerium(III) chloride heptahydrate (1.03 g; 2.76 mmol) in methanol (250 mL) at 0 C was added portion-wise sodium borohydride (~1.2 equiv.) until TLC analysis (petroleum ether/ether 6:4) indicated the disappearance of the starting material. The reaction mixture was poured into saturated ammonium chloride solution (100 mL) and extracted with ether (3100 mL), the organic layer was dried (Na2SO4) and the solvent removed under reduced pressure. Purification was accomplished by chromatographic filtration through silica (petroleum ether/ethyl acetate 10:2) to yield pure (E)-4-phenyl-but-3-en-2-ol (24.77 g; 84%): 1H NMR 7.35-7.12 (5 H, m, arom), 6.50 (1 H, d, J = 15 Hz, 4-H), 6.24 (1 H, dd, J = 15, 7 Hz, 3-H), 4.43 (1 H, m, 2-H), 2.45 (1 H, br s, OH), 1.38 (3 H, d, J = 7 Hz, Me); 13C NMR 136.6 (C), 133.5 (CH), 129.1 (CH), 128.4 (CH), 128.1 (CH), 127.6 (CH), 126.3 (CH), 68.7 (CH), 23.3 (CH3);IR (neat) 3413, 3375, 2966, 2889, 1489, 1446, 1358, 1304, 1142, 1057, 964, 933, 876, 752 cm-1; MS (EI) m/z (%) 148 (82, M+), 133 (40), 131 (11), 129 (16), 115 (31), 105 (100), 91 (52), 77 (28), 55 (18), 51 (14); HRMS (EI) 148.08881 (C10H12O requires 148.08882), in accordance with the literature.[2] A solution of 4-phenyl-but-3-en-2-ol (7.40 g; 50 mmol), acetic anhydride (5.2 mL; 55 mmol; 1.1 equiv.), triethylamine (13.9 mL; 100 mmol; 2 equiv), and DMAP (250 mg) in dichloromethane (200 mL) were stirred at room temperature for 24 h. The reaction mixture was washed with 10% hydrochloric acid (350 mL), saturated aqueous sodium hydrogen carbonate (350 mL) and dried (MgSO4). Removal of the solvent and purification by column chromatography (14:1, petroleum ether/ether) gave pure 4 (9.02 g; 95%) as a colourless oil: 1H NMR 7.30 (5 H, m, arom), 6.58 (1 H, d, J = 16 Hz, 3-H), 6.18 (1 H, dd, J = 16, 6.6 Hz, 2-H), 5.53 (1 H, dq, J = 6.6, 6.6 Hz, 1-H), 2.04 (3 H, s, CO2Me), 1.39 (3 H, d, J = 6.6 Hz, Me); 13C NMR 170.1 (C), 136.2 (C), 131.4 (CH), 128.6 (CH), 128.2 (CH), 128.0 (CH), 126.7 (CH), 70.8 (CH), 21.2 (CH3), 20.2 (CH3);IR (neat) 3032, 2938, 2854, 1732, 1493, 1450, 1369, 1227, 1014, 957, 752 cm-1; MS (EI) m/z (%) 190 (8, M+), 165 (40), 148 (100), 133 (25), 132 (55), 130 (61), 129 (95), 123 (54), 115 (78), 105 (31), 98 (24), 91 (62), 79 (38), 57 (21); HRMS (EI) 190.09940 (C12H14O2 requires 190.09938), in accordance with the literature.[2]
(R)-(+)-(E)-2-Acetoxy-4-phenyl-but-3-ene (R)-(+)-4. The enantiomerically enriched alcohol(R)-4-phenyl-but-3-en-2-ol,[3] required for the synthesis of (R)-(+)-4, was obtained from the racematefollowing our procedure:[3]to a solution of titanium(IV) isopropoxide (4.60 mL; 15.45 mmol) in dry dichloromethane (150 mL), containing 3Å molecular sieves (6.0 g) was added (+)-diisopropyl tartrate (3.90 mL; 18.6 mmol) at 20 C and the mixture was stirred at this temperature for 20 min. To the reaction mixture was added a solution of (E)-4-phenyl-3-buten-2-ol (2.29 g; 15.5 mmol) in dichloromethane (20 mL), followed by the dropwise addition of t-butyl hydroperoxide (1.69 mL; 9.27 mmol; 5.5 M in nonane) at 20 C. The mixture was stirred at -20 C for 3 h and then poured into a cold (0 C) mixture of acetone/water (70:1; 355 mL) and allowed to warm to room temperature with stirring. The acetone solution was filtered through a column of aluminium oxide (105 cm) and the solvent was removed under reduced pressure. The residue was chromatographed on silica (110 g; petroleum ether/ethyl acetate 20:1) to afford (R)-4-phenyl-but-3-en-2-ol (1.19 g; 52%): []D +21.43 (c, 1.8 g; CHCl3) corresponding to 86% ee in accordance with the literature.[3] The acetate was prepared in the same manner as described for ()-4 (95%), giving identical spectroscopic data.
(E)-1-Acetoxy-1,3-diphenylprop-2-ene 6. Method A. A solution of phenylmagnesium bromide was prepared under nitrogen from dry magnesium turnings (1.215 g, 50 mmol) in ether (35 mL) and bromobenzene (7.85 g, 50 mmol) in ether (45 mL). To the Grignard mixture was added a solution of cinnamaldehyde (6.608 g; 50 mmol) in ether (30 mL), the mixture was stirred at reflux for 2 h, then cooled and poured on to crushed ice. The resulting solution was rendered acidic by the addition of 2M sulfuric acid, extracted with ether (375 mL), and dried (MgSO4). To the solution was added acetic anhydride (5.61 g; 55 mmol), triethylamine (15.18 g; 150 mmol), and DMAP (250 mg; 2 mmol) in ether (150 mL) and the mixture was stirred at room temperature overnight. The reaction mixture was washed with dil. hydrochloric acid (250 mL), saturated aqueous sodium hydrogen carbonate (3100 mL) and dried (MgSO4). Removal of the solvent under reduced pressure and purification by column chromatography on silica (3.525 cm column; hexane/ether 12:1) gave 6 (9.82 g; 78%) as a pale yellow oil: 1H NMR 7.15-7.43 (10 H, m, 2 arom), 6.63 (1 H, d, J = 15.4 Hz, 3-H), 6.45 (1 H, d, J = 6.9 Hz, 1-H), 6.33 (1 H, dd, J = 15.4 and 6.9 Hz, 1-H), 2.10 (3 H, s, COMe); 13C NMR 169.8 (C), 139.2 (C), 136.1 (C), 132.5 (CH), 128.5 (2 CH), 128.1 (CH), 128.0 (CH), 127.3 (CH), 126.9 (CH), 126.6 (CH), 76.0 (CH), 21.2 (CH3), in accordance with the literature.[4]
Method B. To a solution of phenylacetaldehyde (4.0 g; 30 mmol) in THF (50 mL) at
-78 °C was added dropwise phenyl lithium (16.7 mL; 1.8 M; 30 mmol in hexane). The mixture was stirred for 1 h and then allowed to warm to rt. The reaction was quenched with saturated aqueous ammonium chloride (30 mL), extracted with ether (345 mL) and the organic layer was dried (MgSO4). To the solution was added triethylamine (4.7 mL; 65 mmol), acetic anhydride (4.4 mL; 40 mmol) and DMAP (300 mg; 25 mmol), the mixture was then stirred at room temperature for 3 h. The mixture was washed with saturated aqueous sodium hydrogen carbonate (350 mL), dried (MgSO4) and the solvent removed under reduced pressure to give a crude oil (6.97 g). Purification by column chromatography on silica (65 g; hexane/ethyl acetate 25:1) gave pure 6 (6.22 g; 82%) as a pale yellow oil: The experimental data were identical to those for the compound prepared by Method A.
Tetracarbonyl-(2,2’-bipyridyl)molybdenum(0) 26a. A suspension of molybdenum hexacarbonyl (10.56 g; 40 mmol) and 2,2-bipyridyl (7.50 g; 48 mmol) in dry toluene (250 mL) was heated at reflux for 2 h. The red coloured solution was allowed to cool, and the solid filtered, washed with toluene (30 mL) and dried overnight in a vacuum oven at 80 C to yield 26a (14.35 g, 98%), as a red crystalline complex: IR (Nujol) (CO) 2005, 1910, 1875, 1815 cm-1, in accordance with the literature.[5]
Tetracarbonyl-(1,10-phenanthroline)molybdenum(0) 26b. Molybdenum hexacarbonyl (10.56 g; 40 mmol) and 1,10-phenanthroline (8.65 g; 48 mmol) in toluene (250 mL) were heated at reflux for 2 h, to yield a red/brown crystalline complex. The solid was taken up into hot acetone and filtered hot to remove a grey precipitate. The solution was reduced to a quarter volume and toluene (20 mL) was added to precipitate a red crystalline complex, which was dried overnight at 80 C in a vacuum oven to yield 26b (13.97 g; 87%): IR (Nujol) (CO) 2000(s), 1895, 1875(sh), 1850, in accordance with the literature.[5]
Tetracarbonyl-(2,2’-bipyridyl)tungsten(0) 27a. A suspension of tungsten hexacarbonyl (3.52 g; 10 mmol) and 2,2-bipyridyl (1.87 g; 12 mmol) in dry xylene (100 mL) was heated at reflux for 4 h. The red/purple coloured solution was allowed to cool and the crystalline product filtered, washed with petroleum ether (50 mL), and dried overnight in a vacuum oven at 80 C to yield 27a (2.75 g, 61%), as a maroon complex: IR (Nujol) (CO) 2001(s), 1920(s), 1878, 1827 cm-1, in accordance with the literature.[5]
Tetracarbonyl-(1,10-phenanthroline)tungsten(0) 27b. Tungsten hexacarbonyl (3.52 g; 10 mmol) and 1,10-phenanthroline (2.16 g; 12 mmol) in xylene (160 mL) were heated at reflux for 4 h. The solution was cooled and filtered to isolate 27b (2.74 g; 58 %) as a maroon complex: IR (Nujol) (CO) 2006(s), 1908(s), 1880(sh), 1830(s) cm-1, in accordance with the literature.[5]
Tricarbonylchloro(trichlorostannyl)-(2,2’-bipyridyl)molybdenum(II) 28a. To a stirred suspension of tetracarbonyl 26a (2.80 g; 7.69 mmol) in dry dichloromethane (25 mL) under a nitrogen atmosphere was added tin(IV) chloride (1 mL; 8.46 mmol; 1.1 equiv.). The solution was stirred at room temperature for 1.5 h, and then filtered. The solid was washed with dichloromethane (10 mL), pentane (210 mL), and dried under vacuum to yield 28a (4.32 g, 90%) as an orange/yellow powder: IR (Nujol) (CO) 2025(s), 1930 cm-1, in accordance with the literature.[6]
Tricarbonylchloro(trichlorostannyl)-(1,10-phenanthroline)molybdenum(II) 28b. Following the same procedure as for 28a, 28b was prepared as an orange/yellow powder (4.64 g; 93%): IR (Nujol) (CO) 2010(s), 1925(br) cm-1, in accordance with the literature.[6]
Tricarbonylchloro(trichlorostannyl)-(2,2’-bipyridyl)tungsten(II) 29a. Following the same procedure as for 28a, 29a was prepared as an orange/yellow powder (4.76 g, 87%): IR (Nujol) (CO) 2015(s), 1920(br) cm-1, in accordance with the literature.[6]
Tricarbonylchloro(trichlorostannyl)-(1,10-phenanthroline)tungsten(II) 29b. Following the same procedure as for 28a, 29b was prepared as an orange/yellow powder (4.64 g, 82%): IR (Nujol) (CO) 2035(s), 1925(br) cm-1, in accordance with the literature.[6]
References and Notes for the Supporting Information
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[2](a) C. F. Nutaitus and J. E. Bernardo, J. Org. Chem., 1989, 54, 5629. (b) I. Flemming, D. Higgins, N. J. Lawrence and A. P. Thomas, J. Chem. Soc., Perkin Trans 1, 1992, 3331.
[3]I. Starý, J. Zajíček and P. Kočovský, Tetrahedron, 1992, 48, 7229.
[4](a) P. R. Auburn, P. B. Mackenzie and B. Bosnich, J. Am. Chem. Soc., 1985, 107, 2033. (b) J. V. Allen, S. J. Coote, G. J. Dawson, C. G. Frost, C. J. Martin and J. M. Williams, J. Chem. Soc., Perkin Trans. 1, 1994, 2065.
[5]M. H. B. Stiddard, Inorg. Chem. 1962, 1, 4712.
[6](a) P. K. Baker and A. Bury, J. Organomet. Chem., 1989, 359, 189. (b) P. K. Baker and A. Quinlan, J. Inorg. Chem., 1989, 162, 179. (c) P. K. Baker and A. Bury, Polyhedron, 1989, 8, 7. (d) M. Cano, M. Panizo, J. A. Campo, J. Tornero and N. Menendez, J. Organomet. Chem., 1993, 463, 121. (e) K. Edgar, J. Chem. Soc., 1968, 2855. (f) K. Edgar, B. F. G. Johson, J. Lewis and S. B. Wild, J. Chem. Soc., 1968, 2851.