Stemmler and Bolm
128.2, 128.3, 128.4, 128.5, 128.6, 129.6 (d, J ) 26.7 Hz), 131.5
(d, J ) 15.4 Hz), 133.1 (dd, J ) 18.4, 2.1 Hz), 133.6 (d, J )
21.7 Hz), 134.4 (d, J ) 21.2 Hz), 135.8 (d, J ) 21.7 Hz), 136.9
(d, J ) 18.6 Hz), 137.5 (d, J ) 7.2 Hz), 138.2 (d, J ) 7.4 Hz),
193.5 (3C); 31P NMR (121 MHz, CDCl3) δ -29.8 (d, J ) 22.9
Hz), 10.5 (d, J ) 23.0 Hz); IR (KBr, cm-1) ν 3059, 2020, 1922,
1479, 1432, 1375, 1164, 1091, 1032, 743, 695, 602, 505, 466;
MS (EI) m/z (%) 732 (M+, 6), 730 ((M - 2)+, 3), 704 ((M - CO)+,
100), 702 ((M - CO - 2)+, 57), 676 ((M - 2CO)+, 19), 674 (M
- 2CO - 2)+, 15), 519 (38), 461 (24). Anal. Calcd for
C34H27O3P2Re: C, 55.81; H, 3.72. Found: C, 55.55; H, 4.08.
pentane/ethyl acetate 9:1), giving the major diasteromer of 8b
as a colorless solid (78 mg, 63% yield).
(R,Sp)-2-(1′-Hydroxyethyl)diphenylphosphinocyr-
hetrene [(R,Sp)-8b, Major Diastereomer]: mp 108-111 °C;
1
[R]23 -129 (c 0.45, CHCl3); H NMR (400 MHz, C6D6) δ 1.32
D
(d, J ) 6.9 Hz, 3H), 1.39 (s, 1H), 4.24 (t, J ) 2.7 Hz, 1H), 4.68
(dd, J ) 2.7, 1.7 Hz, 1H), 4.92 (mc, 1H), 5.21 (qd, J ) 6.8, 4.1
Hz, 1H), 7.02-7.19 (m, 6H), 7.31 (mc, 2H), 7.46 (mc, 2H); 13C
NMR (100 MHz, C6D6) δ 25.1, 50.1 (d, J ) 12.3 Hz), 80.5, 86.6
(d, J ) 2.3 Hz), 93.9 (d, J ) 5.3 Hz), 97.5 (d, J ) 24.4 Hz),
116.0 (d, J ) 23.6 Hz), 128.5 (d, J ) 6.9 Hz, 2C), 128.89, 128.93
(d, J ) 7.6 Hz, 2C), 129.9, 133.1 (d, J ) 18.3 Hz, 2C), 134.8 (d,
J ) 21.4 Hz, 2C), 136.5 (d, J ) 8.4 Hz), 137.5 (d, J ) 8.6 Hz),
193.2 (3C, CO); 31P NMR (162 MHz, C6D6) δ -27.4 (s); IR (KBr,
cm-1) ν 3675, 3445, 3390, 2931, 2026, 1922, 1430, 1230, 1166,
1091, 1035, 827, 742, 694, 595, 502; MS (EI) m/z (%) 546 ((M
- H2O)+, 43), 544 ((M - H2O - 2)+, 29), 518 ((M - H2O -
CO)+, 57), 516 ((M - H2O - CO - 2)+, 36), 462 ((M - H2O -
3CO)+, 100), 382 (36), 230 (43). Anal. Calcd for C22H18O4PRe:
C, 46.89; H, 3.22. Found: C, 46.59; H, 3.62.
(R,Sp)-2-(1′-Di-tert-butylphosphinoethyl)diphenylphos-
phinocyrhetrene [(R,Sp)-7b]. Following GP 3 using (R,Sp)-
6b (80 mg, 0.11 mmol) afforded the title compound as a
colorless foam (60 mg, 78%). In this case, all operations were
conducted under argon: mp 145-147 °C dec; [R]24 -177 (c
D
0.28, CHCl3); 1H NMR (300 MHz, C6D6) δ 0.96 (d, J ) 10.7
Hz, 9H), 1.12 (d, J ) 10.8 Hz, 9H), 1.41 (dd, J ) 7.3, 2.6 Hz,
3H), 3.66 (br q, J ) 7.2 Hz, 1H), 4.36 (td, J ) 2.7, 0.9 Hz, 1H),
4.82 (mc, 1H), 5.04 (dd, J ) 2.9, 1.7 Hz, 1H), 7.02-7.13 (m,
6H), 7.35-7.41 (m, 2H), 7.51-7.57 (m, 2H); 13C NMR (75 MHz,
C6D6) δ 17.8, 29.8 (dd, J ) 36.4, 5.5 Hz), 31.5 (d, J ) 13.5 Hz,
3C), 31.6 (d, J ) 14.7 Hz, 3C), 34.3 (d, J ) 5.3 Hz), 34.7 (d, J
) 10.7 Hz), 78.9, 86.9, 94.8 (d, J ) 6.3 Hz), 96.8 (d, J ) 15.7
Hz), 121.1 (d, J ) 19.2 Hz), 127.7-128.4 (3C), 128.8 (d, J )
7.7 Hz, 2C), 129.5, 133.4 (dd, J ) 17.9, 3.2 Hz, 2C), 135.3 (d,
J ) 21.9 Hz, 2C), 139.3 (d, J ) 8.5 Hz), 139.7 (d, J ) 9.4 Hz),
194.5 (3C, CO); 31P NMR (121 MHz, C6D6) δ -29.5 (d, J )
55.1 Hz), 51.6 (d, J ) 55.0 Hz); IR (KBr, cm-1) ν 2942, 2863,
2391, 2021, 1911, 1473, 1435, 1038, 810, 744, 697, 603, 506;
MS (EI) m/z (%) 692 (M+, 2), 690 ((M - 2)+, 2), 635 ((M -
t-Bu)+, 100), 633 ((M - t-Bu - 2)+, 59), 579 ((M - t-Bu -
2CO)+, 21), 577 ((M - t-Bu - 2CO - 2)+, 12). Anal. Calcd for
C30H35O3P2Re: C, 52.09; H, 5.10. Found: C, 52.36; H, 5.43.
(R,Sp)-2-(1′-Methoxyethyl)diphenylphosphinocyr-
hetrene [(R,Sp)-8a, Major Diastereomer]. Following GP 4
using (R,Sp)-5a (0.188 mmol scale) and MeOH (2 mL) afforded
(R,Sp)-8a as a colorless solid (40 mg, 37% yield) after purifica-
tion by column chromatography (silica gel, pentane/ethyl
acetate 19:1 f 9:1): mp 114-117 °C; [R]23 -126 (c 0.44,
D
CHCl3); 1H NMR (400 MHz, C6D6) δ 1.13 (d, J ) 6.4 Hz, 3H),
2.73 (s, 3H), 4.30 (t, J ) 2.7 Hz, 1H), 4.43 (qd, J ) 6.4, 3.0 Hz,
1H), 4.65 (mc, 1H), 5.02 (mc, 1H), 7.01-7.10 (m, 6H), 7.27-
7.32 (m, 2H), 7.48-7.52 (m, 2H); 13C NMR (100 MHz, C6D6) δ
18.6, 56.0, 71.7 (d, J ) 7.9 Hz), 80.3, 86.8 (d, J ) 2.9 Hz), 93.3
(d, J ) 5.9 Hz), 97.7 (d, J ) 23.0 Hz), 116.9 (d, J ) 22.9 Hz),
128.4 (d, J ) 6.1 Hz, 2C), 128.6, 128.9 (d, J ) 7.6 Hz, 2C),
129.8, 132.9 (d, J ) 18.3 Hz, 2C), 135.0 (d, J ) 20.8 Hz, 2C),
136.4 (d, J ) 9.2 Hz), 138.5 (d, J ) 9.9 Hz), 193.9 (3C); 31P
NMR (121 MHz, C6D6) δ -24.5 (s); IR (KBr, cm-1) ν 3452, 3416,
3371, 2978, 2930, 2020, 1920, 1431, 1242, 1177, 1091, 749, 696,
597, 500; MS (EI) m/z (%) 578 (M+, 51), 576 ((M - 2)+, 33),
563 ((M - CH3)+, 100), 561 ((M - CH3 - 2)+, 60), 550 ((M -
CO)+, 55), 548 ((M - CO - 2)+, 35), 520 (25), 518 (35), 462
(68). Anal. Calcd for C23H20O4PRe: C, 47.83; H, 3.49. Found:
C, 48.19; H, 3.60.
(R,Sp)-2-(1′-Diphenylphosphinoethyl)-[bis(3′′,5′′-dime-
thylphenyl)phosphino]cyrhetrene [(R,Sp)-7c]. Following
GP 3 using (R,Sp)-6c (125 mg, 0.153 mmol) afforded the title
compound after purification by column chromatography (neu-
tral alumina, pentane/Et2O 9:1) under N2 as colorless foam
(84 mg, 70%): mp 76-79 °C dec; [R]22 -205 (c 0.25, CHCl3);
D
1H NMR (300 MHz, C6D6) δ 1.19 (dd, J ) 7.0, 5.1 Hz, 3H),
2.08 (s, 6H), 2.13 (s, 6H), 4.24 (mc, 1H), 4.33 (t, J ) 2.7 Hz,
1H), 4.50 (br s, 1H), 5.21 (mc, 1H), 6.70 (s, 1H), 6.79 (s, 1H),
6.89-6.91 (m, 3H), 7.03-7.13 (m, 3H), 7.16-7.22 (m, 2H), 7.26
(s, 1H), 7.29 (s, 1H), 7.35-7.41 (m, 2H), 7.43 (s, 1H), 7.46 (s,
1H); 13C NMR (75 MHz, C6D6) δ 18.3, 21.3 (2C), 21.4 (2C), 29.8
(dd, J ) 21.6, 9.8 Hz), 79.3, 86.6, 93.8 (d, J ) 4.4 Hz), 97.6 (d,
J ) 25.0 Hz), 121.6 (d, J ) 24.3 Hz), 128.6 (d, J ) 4.2 Hz, 2C),
129.8 (2C), 130.6 (2C), 131.4 (2C), 131.5 (2C), 131.7 (2C), 132.7
(d, J ) 21.2 Hz, 2C), 134.7 (d, J ) 22.6 Hz, 2C), 136.2 (d, J )
22.0 Hz, 2C), 137.3 (d, J ) 19.0 Hz, 2C), 137.6 (d, J ) 6.9 Hz),
137.8 (d, J ) 6.7 Hz), 138.4 (d, J ) 8.3 Hz), 138.6 (d, J ) 8.4
Hz), 194.4 (3C); 31P NMR (121 MHz, C6D6) δ -28.7 (d, J )
25.3 Hz), 10.8 (d, J ) 25.2 Hz); IR (KBr, cm-1) ν 2020, 1921,
1584, 1435, 1163, 1124, 1038, 848, 743, 694, 599, 505; MS (EI)
m/z (%) 788 (M+, 11), 785 ((M - 2)+, 6), 776 (36), 760 ((M -
CO)+, 100), 758 ((M - CO - 2)+, 59), 732 ((M - 2CO)+, 27),
730 ((M - 2CO - 2)+, 17), 519 (46), 517 (38). Anal. Calcd for
C38H35O3P2Re: C, 57.93; H, 4.48. Found: C, 57.92; H, 4.83.
General Procedure for the Rh-Catalyzed, Asymmetric
1,4-Addition Reaction. Under argon, a Schlenk tube was
filled with Rh(acac)(C2H4)2 (3.10 mg, 12.0 µmol, 3 mol %),
cyrhetrene 7a (9.07 mg, 12.4 µmol, 3.1 mol %), and PhB(OH)2
(10a, 244 mg, 2.00 mmol, 5.0 equiv). The mixture was dissolved
in dioxane/water (10:1, 1.1 mL). After the addition of 2-cyclo-
hexen-1-one (9A, 38.5 mg, 39.0 µL, 0.400 mmol), the solution
was heated to 100 °C for 5 h. The solvent was removed in
vacuo, and the brown residue was suspended in ethyl acetate
(5 mL) and aqueous NaHCO3 (5 mL). The aqueous layer was
extracted with ethyl acetate (10 mL), and the combined organic
layers were dried over MgSO4. After removal of the solvent,
the crude product was purified by column chromatography
(silica gel, pentane/ethyl acetate 6:1) to afford 3-phenylcyclo-
hexanone (11Aa) as a colorless oil (65 mg, 93%).
General Procedure (GP 4) for the Synthesis of P,O
Ligands 8a and 8b. Ethyl chloroformate (48.0 mg, 42.0 µL,
0.437 mmol, 2.0 equiv) was added dropwise to a solution of
(R,Sp)-2-(1-dimethylaminoethyl)diphenylphosphinocyr-
hetrene [(R,Sp)-5a] (129 mg, 218 µmol) in THF (2 mL) at -40
°C. The reaction mixture was allowed to reach room temper-
ature, and was stirred for 6.5 h. The red solution was then
treated with degassed water (2.00 g, 2.00 mL, 111 mmol, 550
equiv), and was stirred for 1 h. The solution was diluted with
water (4 mL), extracted with Et2O (3 × 10 mL), and dried over
MgSO4. After removal of the solvent, the residue was purified
by column chromatography (deactivated silica gel (Et3N),
3-Phenylcyclohexanone (11Aa).13b 1H NMR (400 MHz,
CDCl3) δ 1.73-1.91 (m, 2H), 2.08-2.17 (m, 2H), 2.34-2.63 (m,
4H), 3.01 (mc, 1H), 7.22-7.26 (m, 3H), 7.31-7.36 (m, 2H). The
enantiomer ratio was determined by HPLC using a chiral
column (Daicel Chiralcel OD-H), heptane/2-propanol 99:1, 0.5
mL/min, 220 nm, 10 °C, 33.73 min (minor), 35.58 min (major).
Asymmetric Hydrogenation of Enamide 12. Under
argon, Rh(COD)2BF4 (2.0 mg, 5.0 µmol, 1.0 mol %) and
cyrhetrene 7a (4.0 mg, 5.5 µmol, 1.1 mol %) were dissolved in
EtOAc (0.4 mL), and the solution was stirred at room tem-
perature for 20 min. A solution of N-(1-phenylvinyl)acetamide
9930 J. Org. Chem., Vol. 70, No. 24, 2005