Copyright Wiley-VCH Verlag GmbH, D-69451 Weinheim, 2000. Angew. Chem. 2000. Supporting Information for Salen as Chiral Activator : Anti vs Syn Switchable Diastereoselection in the Enantioselective Addition of Crotyl Bromide to omatic Aldehydes. Marco Bandini, Pier Giorgio Cozzi,* Achille Umani-Ronchi* Angewandte Chemie General: 1 H NMR spectra were recorded on Varian 200 MHz or Varian 300 MHz spectrometers. Chemical Shifts are reported in ppm from tetramethylsilane with the solvent resonance as the internal standard (deuterochloroform: δ 7.27 ppm). Data are reported as follows: chemical shifts, multiplicity (s = singolet, d = douplet, t = triplet, q = quartet, br = broad, m = multiplet), coupling constants (Hz). 13 C NMR spectra were recorded on a Varian 50 MHz or Varian 75 MHz spectrometers with complete proton decoupling. Chemical shifts are reported in ppm from tetramethylsilane with the solvent as the internal standard (deuterochloroform: δ 77.0 ppm). Mass spectra were performed at an ionizing voltage of 70 ev. Chromatographic purification was done with 240-400 mesh silica gel. Analytical gas chromatography (GC) was performed on a Hewlett-Packard HP 6890 gas chromatograph with a flame ionization detector and split mode capillary injection system, using a Crosslinked 5% PH ME Siloxane (30 m) column or a Megadex5 chiral (25 m) column. Analytical high performance liquid chromatograph (HPLC) was performed on a HP 1090 liquid chromatograph equipped with a variable wavelength UV detector (deuterium lamp 190-600 nm), using a Daicel Chiralcel TM OD column (0.46 cm I.D. x 25 cm) (Daicel Inc.). HPLC grade isopropanol and hexane were used as the eluting solvents. Elemental analyses were carried out by using a EACE 1110 CHNOS analyzer. All the reactions were carried out under a nitrogen atmosphere in flame-dried glassware using standard inert techniques for introducing reagents and solvents. All the aldehydes were distilled prior to use. All the other commercially obtained reagents were used as received. Anhydrous CH 3 CN were purchased from the Fluka Co. S1
Table S1. Influence of the amount of salen on the diastereoselectivity of the chromium catalyzed addition of crotyl bromide to the PhCHO (see Figure 2). Salen (mol%) 8a:9a [a] Syn/Anti ee of 8a [%] [b] ee of 9a [%] [b] 0 12:88 0.136 -- -- 5 13:87 0.149 31 5 10 33:67 0.493 78 5 15 46:54 0.852 74 21 17.5 70:30 2.333 73 24 20 83:17 4.882 89 36 25 77:23 3.348 85 28 30 72:28 2.571 84 29 [a] Determined by GC analysis of the crude reaction mixture and by 1 H NMR analysis after chromatographic purification. [b] Determined by chiral GC analysis. Table S2. Results of the diastereoselective addition of organohalides to aromatic aldehydes in the presence of CrCl 3 (10 mol%) as the catalyst. RCHO R X [b] Yield Product [%] [a] (Anti:Syn) 7a Cinnamoyl chloride 75 [c] 85:15 7a 3-Bromocyclohexene 55 [c] 99:1 7b Crotyl bromide 82 81:19 7c Crotyl bromide 59 88:12 7d Crotyl bromide 78 79:21 7e Crotyl bromide 80 82:12 7f Crotyl bromide 79 84:16 7g Crotyl bromide 69 73:27 7h Crotyl bromide 31 71:29 [a] Isolated yield after desilylation (HCl/THF) and flash chromatography. [b] Determined by GC analysis of the crude reaction mixture and 1 H NMR analysis after chromatographic purification. [c] Isolated yield after desilylation (Bu 4 NF/THF) and flash chromatography. S2
General Procedure A: Catalytic Asymmetric Addition of Stereogenic Organohalides to 7a-h: O H + Hal X "Catalytic System" X >> X CrCl 3 (8 mg,0.05 mmol) and Mn (83 mg, 1.5 mmol) were added to anhydrous CH 3 CN (2 ml) and the mixture was kept for about 5-8 min, then the reaction mixture was stirred until a green-white precipitate was observed. The ligand 1 (55 mg, 0.1 mmol) was introduced followed by dried triethylamine (14 µl, 0.1 mmol) and the resulting brown solution was stirred at room temperature for 1 h. The solution was treated with the appropriate organo halide (0.75 mmol) and the resulting red solution was stirred for 1 h at room temperature. Finally, 7a-h (0.5 mmol) and Me 3 SiCl (95 µl, 0.75 mmol) were added and the mixture was stirred until the complete consumption of the aldehyde (16-24 h, checked by GC). After quenching with a saturated solution of NaHCO 3 (3 ml), the reaction mixture was filtered on a celite bed, and the CH 3 CN was evaporated under reduced pressure. The residue was extracted with Et 2 O (3 x 2 ml) and the organic phases were collected and evaporated under reduced pressure. The oil obtained was dissolved in THF (2 ml) and treated with 0.5 ml of HCl 1N. The mixture was stirred to complete desilylation (checked by TLC). After evaporation of THF, the residue was extracted with Et 2 O. The organic phases were collected, dried over Na 2 SO 4 and concentrated in vacuo to give a brown residue purified by flash chromatography (silica gel, Cyclohexane:Et 2 O). General Procedure B: Synthesis of the O-methyl ether derivatives (12a-g) of 8/9a-g: OMe X X Into a round-bottom flask 2 ml of anhydrous DMF, dry NaH (0.25-0.29 mmol) and the alcohol (8a-g/9a-g mixture) (0.22-0.26 mmol) was introduced at room temperature. The pale yellow suspension was stirred for 15 min then methyl iodine (0.33-0.39 mmol) was added by syringe. The reaction mixture was stirred until complete as monitored by TLC (1-2 h). A saturated solution of NaHCO 3 (2 ml) and 2 ml of Et 2 O were then added, and the organic layer was separated, washed with HCl 1N (2 ml) and brine and dried over Na 2 SO 4. The drying agent was removed by filtration and the filtrate concentrated under reduced pressure. The crude reaction mixture was purified by flash chromatography (silica gel, Cyclohexane:Et 2 O). The addition of the 10 mol% excess of salen just before the crotyl bromide afforded the product in comparable level of stereoselectivity. S3
2-Methyl-1-phenyl-3-en-1-ol (8a): General procedure A followed employing 50 µl of 7a (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (15% Et 2 O in cyclohexane) gave 45 mg (56%) of the title compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 11.71 (anti) and 11.75 (syn) min) provided the diastereomeric ratio syn:anti 83:17. OMe (1-Methoxy-2-methyl-but-3-enyl)-benzene (12a): General procedure B followed employing 45 mg of 8a (0.28 mmol). Purification by flash chromatography (5% Et 2 O in cyclohexane) gave 48 mg (>98%) of the title compound (colorless oil). Separation of the stereoisomers by chiral GC (Megadex5 column, 25 m, flow rate carrier 70 Kpa, method: 80 C isoterm, T r : 21.0 (1S,2R), 22.0 (1R,2S), 24.6 (1R,2R) and 25.1 (1S,2S) min) provided the diastereomeric ratio syn:anti 83:17 and the enantiomeric ratios: (syn 1R,2S ):(syn 1S,2R ) = 94.5:5.5 (89% ee), (anti 1S,2S ):(anti 1R,2R ) = 68.0:32.0 (36% ee). MS (EI, 70 ev): m/z 130, 128, 121, 115, 105, 91, 77, 51; 1 H NMR (200 MHz, CDCl 3 ) (syn isomer): δ 7.39-7.23 (m, 5H), 6.00-5.81 (m, 1H), 5.07-4.96 (m, 2H), 3.95 (d, J = 9.00 Hz, 1H), 3.23 (s, 3H), 2.52 (m, 1H), 1.07 (d, J = 6.84 Hz, 3H); (anti isomer, diagnostic signals): δ 3.92 (d, J = 7.42 Hz, 1H), 2.54 (q, J = 7.24 Hz, 1H), 0.85 (d, J = 6.92 Hz, 3H); 13 C NMR (75 MHz, CDCl 3 ) (syn isomer): δ 140.5, 138.1, 127.9, 127.4, 127.3, 114.4, 87.8, 57.0, 44.3, 15.5; (anti isomer, diagnostic signals): δ 114.2, 88.1, 16.4; Anal. Calcd for C 12 H 16 O: C, 81.77; H, 9.15; O, 9.08. Found: C, 81.89; H, 9.10; O, 9.01. 2-Methyl-1-p-tolyl-but-3-en-1-ol (8b): General procedure A followed employing 59 µl of 7b (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (20% Et Me 2 O in cyclohexane) gave 42 mg (48%) of the title compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 12.47 (anti) and 12.51 (syn) min) provided the diastereomeric ratio syn:anti 74:26. Me OMe 1-(1-Methoxy-2-methyl-but-3-enyl)-benzene (12b): General procedure B followed employing 42 mg of 8b (0.24 mmol). Purification by flash chromatography (5% Et 2 O in cyclohexane) gave 45 mg (>98%) of the title compound (colorless oil). S4
Separation of the stereoisomers by chiral GC (Megadex5 column, 25 m, flow rate carrier 70 Kpa, method: 80 C isoterm, T r : 40.2 (1S,2R), 41.5 (1R,2S), 40.7 (1R,2R) and 50.5 (1S,2S) min) provided the diastereomeric ratio syn:anti 74:26 and the enantiomeric ratios: (syn 1R,2S ):(syn 1S,2R ) = 92.5:7.5 (85% ee), (anti 1S,2S ):(anti 1R,2R ) = 60.0:40.0 (20% ee). MS (EI, 70 ev): m/z 159, 135, 119, 105, 91, 65, 51; 1 H NMR (300 MHz, CDCl 3 ) (syn isomer): δ 7.27-7.14 (m, 4H), 5.95-5.81 (m, 1H), 4.95 (dd, J 1 = 5.7 Hz, J 2 = 1.4 Hz, 1H), 4.90 (d, J = 1.4 Hz, 1H), 3.93 (d, J = 6.60 Hz, 1H), 3.21 (s, 3H), 2.55-2.42 (m, 1H), 2.36 (s, 3H), 1.02 (d, J = 6.60 Hz, 3H); (anti isomer, diagnostic signals): δ 3.89 (d, J = 7.50 Hz, 1H), 3.19 (s, 3H), 0.87 (d, J = 6.90 Hz, 3H); 13 C NMR (75 MHz, CDCl 3 ): δ 140.5, 137.3, 136.9, 128.6, 127.4, 114.3, 87.6, 56.9, 44.2, 21.2, 15.5; (anti isomer, diagnostic signals): δ 114.1, 88.0, 44.3, 16.4; Anal. Calcd for C 13 H 18 O: C, 82.06; H, 9.53; O, 8.41. Found: C, 82.00; H, 9.46; O, 8.54. 1-(4-Fluoro-phenyl)-2-methyl-1-but-3-en-1-ol (8c): General procedure A followed employing 68 µl of 7c (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (15% Et 2 O in cyclohexane) gave 48 mg (53%) of the title F compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 11.45 (anti) and 11.48 (syn) min) provided the diastereomeric ratio syn:anti 74:26. OMe 1-Fluoro-4-(1-methoxy-2-methyl-but-3-enyl)-benzene (12c): General procedure B followed employing 48 mg of 8c (0.25 mmol). Purification by flash chromatography (5% Et 2 O in cyclohexane) gave 51 mg (>98%) of the title compound (colorless oil). F Separation of the stereoisomers by chiral GC (Megadex5 column, 25 m, flow rate carrier 70 Kpa, method: 110 C isoterm, T r : 5.1 (1S,2R), 5.3 (1R,2S), 5.8 (1R,2R) and 6.0 (1S,2S) min) provided the diastereomeric ratio syn:anti 74:26 and the enantiomeric ratios: (syn 1R,2S ): (syn 1S,2R ) = 95.0:5.0 (90% ee), (anti 1S,2S ):(anti 1R,2R ) = 64.5:36.5 (27% ee). MS (EI, 70 ev): m/z 146, 140, 139, 133, 123, 109, 95, 91, 75, 51; 1 H NMR (300 MHz, CDCl 3 ) (syn isomer): δ 7.26-7.19 (m, 2H), 7.07-7.00 (m, 2H), 5.65 (ddd, J 1 7.20 Hz, J 2 = 10.80 Hz, J 3 = 18.30 Hz, 1H), 4.94-4.87 (m, 2H), 3.93 (d, J = 6.60 Hz, 1H), 3.21 (s, 3H), 2.50 (q, J = 7.20 Hz, 1H), 1.05 (d, J = 6.90 Hz, 3H); (anti isomer, diagnostic signals): δ 3.92 (d, J = 5.40 Hz, 1H), 3.19 (s, 3H), 0.84 (d, J = 6.90 Hz, 3H); 13 C NMR (50 MHz, CDCl 3 ): δ 159.4, 140.2, 129.1, 128.9, 115.1, 114.8, 87.2, 56.9, 44.3, 15.6; (anti isomer, diagnostic signals): δ140.9, 115.2, 114.6, 87.5, 16.3. Anal. Calcd for C 12 H 15 FO: C, 74.20; H, 7.78; O, 8.24. Found: C, 74.32; H, 7.74; O, 8.13. 1-(4-Chloro-phenyl)-2-methyl-1-but-3-en-1-ol (8d): General procedure A followed employing 70 mg of 7d (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (20% Et 2 O in cyclohexane) gave 45 mg (46%) of the title Cl compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 13.65 (anti) and 13.68 (syn) min) provided the diastereomeric ratio syn:anti 61:39. S5
OMe 1-Chloro-4-(1-methoxy-2-methyl-but-3-enyl)-benzene (12d): General procedure B followed employing 45 mg of 8d (0.23 mmol). Purification by flash chromatography (5% Et 2 O in cyclohexane) gave 47 mg (>98%) of the title compound (colorless oil). Cl Separation of the stereoisomers by chiral GC (Megadex5 column, 25 m, flow rate carrier 70 Kpa, method: 100 C isoterm, T r : 31.2 (1S,2R), 32.6 (1R,2S), 36.3 (1R,2R) and 38.4 (1S,2S) min) provided the diastereomeric ratio syn:anti 61:39 and the enantiomeric ratios: (syn 1R,2S ):(syn 1S,2R ) = 91.0:9.0 (82% ee), (anti 1S,2S ):(anti 1R,2R ) = 62.0:38.0 (24% ee). MS (EI, 70 ev): m/z 157, 155, 139, 110, 91, 51; 1 H NMR (200 MHz, CDCl 3 ) (syn isomer): δ 7.50-7.44 (m, 2H), 7.16-7.10 (m, 2H), 5.70-5.56 (m, 1H), 5.06-5.01 (m, 2H), 3.91 (d, J = 6.30 Hz, 1H), 3.20 (s, 3H), 2.46 (q, J = 6.88 Hz, 1H), 1.04 (d, J = 6.76 Hz, 3H); (anti isomer, diagnostic signals): δ 5.84 (ddd, J 1 = 7.42 Hz, J 2 = 10.78 Hz, J 3 = 17.00 Hz, 1H), 4.95-4.86 (m, 2H), 3.91 (d, J = 6.96 Hz, 1H), 0.85 (d, J = 6.92 Hz, 3H); 13 C NMR (50 MHz, CDCl 3 ) (syn isomer): δ 141.0, 140.6, 131.1, 129.2, 121.3, 114.7, 87.2, 57.1, 41.2, 15.4; (anti isomer, diagnostic signals): δ 140.0, 139.5, 131.2, 129.2, 121.2, 87.5, 44.2, 16.2; Anal. Calcd for C 12 H 15 ClO: C, 68.40; H, 7.18; O, 7.59. Found: C, 68.51; H, 7.14; O, 7.70. 1-(4-Bromo-phenyl)-2-methyl-but-3-en-1-ol (8e): General procedure A followed employing 92 mg of 7e (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (20% Et 2 O in cyclohexane) gave 52 mg (43%) of the title Br compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 14.68 (anti) and 14.75 (syn) min) provided the diastereomeric ratio syn:anti 72:28. OMe 1-Bromo-4-(1-methoxy-2-methyl-but-3-enyl)-benzene (12e): General procedure B followed employing 52 mg of 8e (0.22 mmol). Purification by flash chromatography (5% Et 2 O in cyclohexane) gave 54 mg (>98%) of the title compound (colorless oil). Br Separation of the stereoisomers by chiral GC (Megadex5 column, 25 m, flow rate carrier 70 Kpa, method: 110 C for 28 min, ramp @ 3 C/min to 130 C for 20 min, T r : 29.8 (1S,2R), 31.0 (1R,2S), 31.8 (1R,2R) and 32.5 (1S,2S) min) provided the diastereomeric ratio syn:anti 72:28 and the enantiomeric ratios: (syn 1R,2S ):(syn 1S,2R ) = 91.0:9.0 (82% ee), (anti 1R,2R ):(anti 1S,2S ) = 64.0:36.0 (28% ee). MS (EI, 70 ev): m/z 201, 199, 187, 185, 159, 157, 120, 94, 92, 51; 1 H NMR (200 MHz, CDCl 3 ) (syn isomer): δ 7.50-7.46 (m, 2H), 7.17-7.10 (m, 2H), 5.75-5.56 (m, 1H), 4.96-4.83 (m, 2H), 3.92 (d, J = 6.30 Hz, 1H), 3.21 (s, 3H), 2.47 (q, J 1 = 6.60 Hz, 1H), 1.04 (d, J = 6.80, 3H); (anti isomer, diagnostic signals): δ 3.90 (d, J = 6.88 Hz, 1H), 0.86 (d, J = 6.88, 3H); 13 C NMR (50 MHz, CDCl 3 ): δ 140.6, 139.5, 131.1, 129.2, 121.2, 114.9, 87.2, 57.1, 44.2, 15.4; (anti isomer, diagnostic signals): δ 140.0, 131.2, 128.5, 114.7, 87.5, 56.7, 41.2, 16.2; Anal. Calcd for C 12 H 15 BrO: C, 56.49; H, 5.93; O, 6.27. Found: C, 56.40; H, 5.88; O, 6.27. Br 1-(3-Bromo-phenyl)-2-methyl-but-3-en-1-ol (8f): General procedure A followed employing 58 µl of 7f (0.50 mmol) and trcrotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (20% Et 2 O in cyclohexane) gave 59 mg (49%) of the title compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, S6
method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 14.32 (anti) and 14.35 (syn) min) provided the diastereomeric ratio syn:anti 66:34. Br Ph OAc (S)-(+)-Acetoxy-phenyl-acetic acid 1-(3-bromo-phenyl)-2-methyl-but-3-enyl ester O O (13): The O-ester was synthesized by adding dropwise the mandelic chloride (1.2 eq.) to a solution of 8f (1eq.), DMAP (0.1 eq), and pyridine (few drops) in anhydrous CH 2 Cl 2 at 0 C. The enantiomeric excess was determination by 1 H NMR analysis. Diagnostic signals (300 MHz, CDCl 3 ) : δ syn 0.79 (d, J = 6.90 Hz, 3H), syn 1.02 (d, J = 6.90 Hz, 3H), anti 0.74 (d, J = 6.90 Hz, 3H), anti 0.91 (d, J = 6.90 Hz, 3H). Ee syn = 70%, ee anti = 43%; Anal. Calcd for C 21 H 21 BrO 4 : C, 60.44; H, 5.07; O, 15.34. Found: C, 60.32; H, 5.03; O, 15.32. 1-(4-Methoxy-phenyl)-2-methyl-but-3-en-1-ol (8g): General procedure A followed employing 57 µl of 7g (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (20% Et 2 O in cyclohexane) gave 50 mg (52%) of the title MeO compound (pale yellow oil). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 14.25 (anti) and 14.28 (syn) min) provided the diastereomeric ratio syn:anti 60:40. OMe 1-Methoxy-4-(1-methoxy-2-methyl-but-3-enyl)-benzene (12g): General procedure B followed employing 50 mg of 8g (0.26 mmol). Purification by flash chromatography (5% Et 2 O in cyclohexane) gave 53 mg (>98%) of the title compound (colorless oil). MeO Separation of the stereoisomers by chiral GC (Megadex5 column, 25 m, flow rate carrier 70 Kpa, method: X C isoterm, T r : 47.0 (1S,2R), 47.8 (1R,2S), 54.2 (1R,2R), 56.5 (1S,2S) min) provided the diastereomeric ratio syn:anti 60:40 and the enantiomeric ratios: (syn 1R,2S ):(syn 1S,2R ) = 79:21 (58% ee), (anti 1S,2S ):(anti 1R,2R ) = 57.5:42.5 (15% ee). MS (EI, 70 ev): m/z 151, 136, 109, 91, 77, 65; 1 H NMR (200 MHz, CDCl 3 ) (syn isomer): δ 7.26-7.15 (m, 2H), 6.91-6.86 (m, 2H), 5.75-5.70 (m, 1H), 5.11-4.90 (m, 2H), 3.92-3.85 (m, 1H), 3.82 (s, 3H), 3.19 (s, 3H), 2.59-2.42 (m, 1H), 1.05 (d, J = 6.68 Hz, 3H); (anti isomer, diagnostic signals): δ 3.88 (m, 1H), 3.18 (s, 3H), 0.83 (d, J = 6.7 Hz, 3H); 13 C NMR (50 MHz, CDCl 3 ): δ 140.6, 128.6, 127.9, 114.4, 113.3, 87.4, 56.7, 55.2, 44.2, 15.6; (anti isomer, diagnostic signals): δ 141.5, 127.3, 114.2, 113.5, 87.7, 44.3, 16.4; Anal. Calcd for C 13 H 18 O 2 : C, 75.69; H, 8.80; O, 15.51. Found: C, 75.77; H, 8.74; O, 15.49. Ph 1-Biphenyl-4-yl-2-methyl-but-3-en-1-ol (8h): General procedure A followed employing 91 mg of 7h (0.50 mmol) and crotyl bromide 77 µl (0.75 mmol). Purification by flash chromatography (15% Et 2 O in cyclohexane) gave 56 mg (47%) of the title compound. S7
Separation of the stereoisomers by chiral HPLC (Daicel Chiralcel TM OD column, flow rate 0.5 ml/min, 2% ipr, 98% hexane, T r : 22.8 (1S,2S), 23.6 (1R,2S), 24.8 (1R,2R) and 26.4 (1S,2R) min) provided the diastereomeric ratio syn:anti 71:29 and the enantiomeric ratios: (syn 1R,2S ):(syn 1S,2R ) = 92.0:8.0 (84% ee), (anti 1S,2S ):(anti 1R,2R ) = 58.0:42.0 (16% ee). 1 H NMR (300 MHz, CDCl 3 ) (syn isomer): δ 7.61-7.55 (m, 4H), 7.42-7.31 (m, 5H), 5.88-5.76 (m, 1H), 5.13-5.08 (m, 2H), 4.69 (br, 1H), 2.65-2.58 (m, 1H), 1.07 (d, J = 6.90 Hz, 3H); (anti isomer, diagnostic signals): δ 4.20 (d, J = 8.10 Hz, 1H), 0.93 (d, J = 6.90 Hz, 3H); 13 C NMR (50 MHz, CDCl 3 ): δ 140.8, 140.2, 130.8, 129.0, 128.7, 127.6, 127.0, 126.9, 126.7, 115.6, 77.0, 44.6, 14.0; (anti isomer, diagnostic signals): δ 141.6, 140.6, 116.9, 46.2, 16.5; Anal. Calcd for C 17 H 18 O: C, 85.67; H, 7.61; O, 6.71. Found: C, 85.52; H, 7.54; O, 6.94. 1,2-Diphenyl-but-3-en-1-ol (14): General procedure A followed employing 90 mg of 7a (0.5 mmol). and cinnamoyl chloride 72 µl (0.75 mmol) Purification by flash chromatography (15% Et 2 O in cyclohexane) gave 81 mg (72%) of the title compound (white solid). Separation of the diastereoisomers (trimethylsilyl ether derivatives) by GC (Crosslinked 5% PH ME Siloxane column, 30 m, flow rate 15 ml/min, method: 50 C for 2 min, ramp @ 10 C/min to 250 C for 15 min, T r : 16.67 (anti) and 16.73 (syn) min) provided the diastereomeric ratio syn:anti 75:25. Separation of the stereoisomers by chiral HPLC (Daicel Chiralcel TM OD column, flow rate 0.5 ml/min, 2% ipr, 98% hexane, T r : 31.5 (<anti), 33.3 (>anti), 34.4 (<syn) and 36.1 (>syn) min) provided the diastereomeric ratio syn:anti 75:25 and the enantiomeric ratios: syn = 93.0:7.0 (86% ee), anti = 63.0:37.0 (26% ee). 1 H NMR (300 MHz, CDCl 3 ) (syn isomer): δ 7.38-7.13 (m, 9H), 7.05 (d, J = 6.90 Hz, 1H), 5.90 (ddd, J 1 = 7.80 Hz, J 2 = 10.50 Hz, J 3 = 17.40 Hz, 1H), 5.00 (dd, J 1 = 0.60 Hz, J 2 = 9.60 Hz, 1H), 4.90-4.83 (m, 2H), 3.64 (t, J = 8.10 Hz, 1H), 1.93 (d, J = 3.00 Hz, 1H); (anti isomer, diagnostic signals): 4.92 (d, J = 3.00 Hz, 1H), 3.55 (t, J = 8.40 Hz, 1H), 2.29 (d, J = 2.40 Hz, 1H); 13 C NMR (75 MHz, CDCl 3 ): δ 141.5, 140.6, 140.2, 128.7, 127.2, 127.0, 126.9, 126.7, 116.9, 115.6, 76.4, 44.8, 13.9; Anal. Calcd for C 16 H 16 O: C, 85.68; H, 7.19; O, 7.13. Found: C, 85.77; H, 7.15; O, 7.08. Cyclohex-2-enyl-phenyl-methanol (15): General procedure A followed employing 50 µl of 7a (0.5 mmol) and 3-bromocyclohexene 86 µl (0.75 mmol). Purification by flash chromatography (20% Et 2 O in cyclohexane) gave 21 mg (22%) of the title compound. Separation of the stereoisomers by chiral HPLC (Daicel Chiralcel TM OD column, flow rate 0.5 ml/min, 5% ipr, 95% hexane, T r : 13.9 (>anti), 14.5 (<syn), 16.0 (>syn) and 17.0 (<anti) min) provided the diastereomeric ratio syn:anti 75:25 and the enantiomeric ratios: syn = 76.0:24.0 (52% ee), anti = 50.0:50.0. MS (EI, 70 ev): m/z 128, 107, 81, 79, 51; 1 H NMR (200 MHz, CDCl 3 ) (syn isomer): δ 7.39-7.21 (m, 5H), 5.86-5.78 (m, 2H), 4.59 (dd, J 1 = 6.40 Hz, J 2 = 3.38 Hz, 1H), 2.51 (br, 2H), 2.12-1.19 (m, 6H); (anti isomer): δ 5.43-5.63 (m, 2H), 4.48 (dd, J 1 = 6.60 Hz, J 2 = 1.10 Hz, 1H); 13 C NMR (75 MHz, CDCl 3 ): δ 142.2, 130.4, 128.2, 126.4, 77.2, 43.0, 25.3, 23.8, 21.1; (anti isomer): δ 77.7, 42.9, 21.5; Anal. Calcd for C 13 H 16 O: C, 82.94; H, 8.57; O, 8.50. Found: C, 82.88; H, 8.50; O, 8.62. S8