C2 Symmetric Ketone Catalysts for Asymmetric Epoxidation
J . Org. Chem., Vol. 64, No. 17, 1999 6457
(10 mL) was stirred at room temperature for 30 min. The
reaction mixture was then quenched with several drops of
Et3N. The solvents were evaporated, and the residue was
purified by flash chromatography (hexane-ether, 10:1 to 8:1
v/v) to give compound 32 as a colorless oil (1.91 g, 96%): IR
36.19, 28.79, 28.49, 26.47, 24.63, 8.72, 7.70; HRMS for C16H25O7
(M+ + 1) calcd: 329.1600, found 329.1606.
P r ep a r a tion of Keton e 6o. To a solution of 34 (0.5 g, 0.89
mmol) in dry THF (2 mL) was added dropwsie DIBAL-H (1M
in hexane, 2.0 mL, 2 mmol) at -20 °C under N2. Upon stirring
at 0 oC for 1 h, the reaction mixture was quenched with
saturated aqueous NH4Cl, filtered, and washed with ether. The
filtrate was concentrated to give a colorless syrup, which was
then dissolved in dry CH2Cl2 (2 mL). To this solution were
added Ac2O (0.15 mL, 1.59 mmol), Et3N (0.2 mL, 1.43 mmol),
and DMAP (cat.). After stirring at room temperature for 2 h,
the reaction mixture was quenched with saturated aqueous
NH4Cl, extracted with ether, washed with brine, dried (Na2-
SO4), filtered, and concentrated to give a residue. The resulting
residue was dissolved in TBAF (1 M in THF, 3 mL). After being
stirred at room temperature for 30 min, the reaction mixture
was diluted with ether, washed with brine, dried (Na2SO4),
filtered, and purified by flash chromatography (hexane-ether,
3:1 to 1:1 v/v) to give an alcohol as a colorless syrup (0.22 g,
1
(NaCl) 1741 cm-1; H NMR δ 7.80 (dd, J ) 7.8, 1.5 Hz, 2H),
7.68 (dd, J ) 7.8, 1.5 Hz, 2H), 7.48-7.34 (m, 6H), 7.02 (m,
1H), 4.32 (ddd, J ) 7.5, 4.2, 1.8 Hz, 1H), 4.18 (ddd, J ) 7.5,
3.9, 1.5 Hz, 1H), 4.09 (dt, J ) 3.9, 2.1 Hz, 1H), 3.74 (s, 3H),
2.94 (d, J ) 16.2 Hz, 1H), 1.7-1.4 (m, 5H), 1.10 (s, 9H), 0.86
(t, J ) 7.5 Hz, 3H), 0.79 (t, J ) 7.5 Hz, 3H); 13C NMR δ 166.3,
144.2, 136.1, 136.0, 134.2, 133.3, 130.1, 130.0, 128.1, 128.0,
127.8, 112.4, 77.27, 73.01, 71.25, 52.01, 28.82, 28.42, 27.36,
27.03, 19.51, 8.96, 7.79.
Dihydroxylation of 32 (1.7 g, 3.44 mmol) was performed in
a manner similar to that of 17. Diol 33 was obtained as a
colorless syrup (1.68 g, 93%) after purification by flash
chromatography (hexane-ether, 1:1 v/v): [R]23 ) -20.1 (c
D
1.07, CHCl3); IR (NaCl) 3485, 1739 cm-1; 1H NMR δ 7.77 (dd,
J ) 7.9, 1.5 Hz, 2H), 7.70 (dd, J ) 7.9, 1.5 Hz, 2H), 7.47-7.33
(m, 3H), 7.29-7.11 (m, 3H), 4.25 (dd, J ) 9.3, 4.8 Hz, 1H),
4.11 (td, J ) 8.0, 4.3 Hz, 1H), 4.07 (dd, J ) 9.3, 3.9 Hz, 1H),
4.02 (dd, J ) 4.3, 3.9 Hz, 1H), 3.80 (s, 3H), 3.10 (s, 1H, OH),
2.06 (d, J ) 4.8 Hz, 1H, OH), 1.95 (d, J ) 8.0 Hz, 2H), 1.85
(dq, J ) 14.1, 7.5 Hz, 1H), 1.70 (dq, J ) 14.1, 7.5 Hz, 1H),
1.45 (qd, J ) 7.5, 2.4 Hz, 2H), 1.11 (s, 9H), 0.98 (t, J ) 7.5 Hz,
3H), 0.85 (t, J ) 7.5 Hz, 3H); 13C NMR δ 174.5, 136.2, 136.0,
133.8, 133.5, 130.2, 130.1, 128.1, 127.8, 113.9, 77.18, 76.64,
72.85, 72.38, 71.95, 53.43, 36.6, 30.91, 27.98, 27.2, 19.66, 9.06,
8.97. Anal. Calcd for C29H40O7Si: C, 65.89; H, 7.63. Found:
65.60; H, 7.40.
73%): [R]23D ) +9.5 (c 1.0, CHCl3); IR (NaCl) 3464, 1746 cm-1
;
1H NMR δ 4.39 (t, J ) 4.5 Hz, 1H), 4.37-4.26 (m, 2H), 4.24
(d, J ) 4.5 Hz, 1H), 4.16 (d, J ) 11.5 Hz, 1H), 4.06 (d, J )
11.5 Hz, 1H), 2.72 (br s, 1H, OH), 2.11 (dd, J ) 13.5, 5.1 Hz,
1H), 2.04 (s, 3H), 1.79 (dd, J ) 13.5, 9.6 Hz, 1H), 1.69 (qd, J
) 7.5, 2.4 Hz, 2H), 1.60 (q, J ) 7.5 Hz, 2H), 1.37 (s, 3H), 1.35
(s, 3H), 0.88 (t, J ) 7.5 Hz, 3H), 0.85 (t, J ) 7.5 Hz. 3H); 13C
NMR δ 170.8, 112.4, 109.4, 81.21, 76.17, 72.51, 70.81, 69.67,
67.05, 34.29, 28.66, 28.45, 27.60, 26.09, 20.97, 8.74, 7.83.
Swern oxidation of the above alcohol (0.18 g, 0.52 mmol)
and purification by flash chromatography (hexane-ether, 3:1
to 2:1 v/v) gave ketone 6o as a colorless syrup (0.171 g, 97%):
[R]23 ) +19.3 (c 1.0, CHCl3); IR (NaCl) 3472 (hydrate), 1751
D
A solution of diol 33 (1.6 g, 3.06 mmol), 2-methoxypropene
(0.5 mL, 5.2 mmol), and camphorsulfonic acid (cat.) in dry CH2-
Cl2 (10 mL) was stirred at room temperature for 2 h and then
quenched with several drops Et3N. Upon removing solvents
under reduced pressure, the residue was purified by flash
chromatography (hexane-ether, 10:1 v/v) to give compound
cm-1; 1H NMR δ 5.09 (dd, J ) 8.4, 0.9 Hz, 1H), 4.94 (ddd, J )
10.8, 8.4, 4.5 Hz, 1H), 4.32 (s, 1H), 4.26 (d, J ) 11.7 Hz, 1H),
4.04 (d, J ) 11.7 Hz, 1H), 2.22 (dd, J ) 14.0, 4.5 Hz, 1H), 2.10
(s, 3H), 1.75 (qd, J ) 7.5, 1.5 Hz, 2H), 1.66 (qd, J ) 7.5, 2.4
Hz, 2H), 1.58 (s, 3H), 1.41 (s, 3H), 1.39 (dd, J ) 14.0, 10.8 Hz,
1H), 0.92 (t, J ) 7.5 Hz, 3H), 0.90 (t, J ) 7.5 Hz, 3H); 13C
NMR δ 203.4, 170.5, 114.6, 112.9, 84.3, 81.19, 77.82, 73.35,
67.47, 36.71, 29.15, 28.7, 26.98, 26.05, 20.91, 8.78, 7.66. Anal.
Calcd for C17H26O7: C, 59.64; H, 7.65. Found: C, 59.55; H,
7.44.
34 as a colorless oil (1.65 g, 96%): [R]23 ) -21.1 (c 1.56,
D
CHCl3); IR (NaCl) 1741 cm-1
;
1H NMR δ 7.85-7.7 (m, 4H),
7.45-7.3 (m, 6H), 4.58 (d, J ) 5.4 Hz, 1H), 4.28 (ddd, J ) 7.8,
7.8, 4.8 Hz, 1H), 4.22 (dd, J ) 5.4, 4.2 Hz, 1H), 4.15 (dd, J )
7.8, 4.2 Hz, 1H), 3.70 (s, 3H), 2.55 (dd, J ) 13.8, 7.8 Hz, 1H),
2.06 (dd, J ) 13.8, 4.8 Hz, 1H), 1.72 (q, J ) 7.5 Hz, 2H), 1.56
(q, J ) 7.5 Hz, 2H), 1.33 (s, 3H), 1.17 (s, 3H), 1.11 (s, 9H),
0.92 (t, J ) 7.5 Hz, 3H), 0.86 (t, J ) 7.5 Hz, 3H); 13C NMR δ
172.9, 136.5, 136.3, 134.0, 133.7, 130.1, 129.7, 127.7, 127.5,
112.8, 110.1, 82.07, 77.28, 73.06, 70.78, 70.69, 52.66, 33.84,
27.92, 27.27, 27.22, 25.63, 25.10, 19.49, 8.90, 8.80.
P r ep a r a tion of Keton e 6p . To an ice cold solution of 34
(0.51 g, 0.9 mmol) in dry THF (1 mL) was added dropwise CH3-
MgBr (3 M in ether, 1 mL, 3 mmol) under N2. After being
stirred at 0 °C for 30 min and then at room temperature for 4
h, the reaction mixture was quenched with saturated aqueous
NH4Cl, extracted with ether (3 × 20 mL), washed with brine,
dried (Na2SO4), filtered, and concentrated to give a residue.
The resulting residue was dissolved in TBAF (1 M, in THF, 3
mL). After being stirred at room temperature for 30 min, the
reaction mixture was diluted with ether, washed with brine,
dried (Na2SO4), filtered, and purified by flash chromatography
(hexane-ether, 3:1 to 2:1 v/v) to give an alcohol as a colorless
A solution of 34 (0.5 g, 0.89 mmol) in TBAF (1 M in THF, 3
mL) was stirred at room temperature for 1 h and then diluted
with ether and saturated aqueous NH4Cl. The ether layer was
separated, and the aqueous layer was extracted twice with
ether. The combined extracts were washed with brine, dried
(Na2SO4), filtered, concentrated, and purified by flash chro-
matography (hexane-ether, 2:1 to 1:1 v/v) to give the alcohol
as a colorless syrup (0.12 g, 41%): [R]23D ) -6.0 (c 0.5, CHCl3);
syrup (0.28 g, 93%): [R]23 ) +15.2 (c 1.1, CHCl3); IR (NaCl)
D
3454 cm-1; H NMR δ 4.64 (d, J ) 4.2 Hz, 1H), 4.51 (dd, J )
1
4.8, 4.2 Hz, 1H), 4.48 (ddd, J ) 10.5, 7.5, 6.0 Hz, 1H), 4.39
(dd, J ) 7.5, 4.8 Hz, 1H), 2.95 (br s, 1H, OH), 2.66 (br s, 1H,
OH), 2.09 (dd, J ) 13.5, 6.0 Hz, 1H), 1.87 (dd, J ) 13.5, 10.5
Hz, 1H), 1.76 (qd, J ) 7.5, 4.2 Hz, 2H), 1.67 (q, J ) 7.5 Hz,
2H), 1.42 (s, 6H), 1.30 (s, 3H), 1.22 (s, 3H), 0.95 (t, J ) 7.5 Hz,
3H), 0.92 (t, J ) 7.5 Hz, 3H); 13C NMR δ 112.4, 109.1, 87.94,
75.30, 72.8, 72.07, 71.69, 66.54, 34.01, 28.94, 28.85, 28.26, 27.4,
26.78, 25.66, 8.87, 7.97.
IR (NaCl) 3530, 1742 cm-1 1H NMR δ 4.91 (d, J ) 4.0 Hz,
;
1H), 4.41 (ddd, J ) 8.7, 8.1, 6.3 Hz, 1H), 4.33 (t, J ) 4.0 Hz,
1H), 4.35-4.25 (m, 1H), 3.81 (s, 3H), 2.68 (br s, 1H, OH), 2.34
(dd, J ) 13.8, 6.3 Hz, 1H), 2.27 (dd, J ) 13.8, 8.7 Hz, 1H),
1.74 (q, J ) 7.5 Hz, 2H), 1.64 (q, J ) 7.5 Hz, 2H), 1.44 (s, 3H),
1.29 (s, 3H), 0.93 (t, J ) 7.5 Hz, 3H), 0.90 (t, J ) 7.5 Hz, 3H);
13C NMR δ 173.6, 112.5, 110.1, 82.12, 76.60, 72.42, 70.19,
67.96, 53.11, 33.82, 28.28, 27.86, 26.89, 24.63, 8.84, 7.91.
Swern oxidation of the above alcohol (0.25 g, 0.758 mmol)
and purification by flash chromatography (hexane-ether 5:1
Swern oxidation of the above alcohol (0.03 g, 0.09 mmol)
and purification by flash chromatography (hexane-ether, 5:1
to 1:1 v/v) gave ketone 6n as a colorless syrup (0.028 g, 94%):
[R]23D ) -1.26 (c 0.87, CHCl3); IR (NaCl) 3491 (hydrate), 1754
cm-1; 1H NMR δ 5.02 (d, J ) 8.4 Hz, 1H), 4.88 (ddd, J ) 10.0,
8.4, 4.5 Hz, 1H), 4.75 (s, 1H), 3.81 (s, 3H), 2.38 (dd, J ) 14.4,
4.5 Hz, 1H), 1.78 (dd, J ) 14.4, 10.0 Hz, 1H), 1.73 (q, J ) 7.5
Hz, 2H), 1.63 (q, J ) 7.5 Hz, 2H), 1.58 (s, 3H), 1.34 (s, 3H),
0.91 (t, J ) 7.5 Hz, 3H), 0.89 (t, J ) 7.5 Hz, 3H); 13C NMR δ
202.3, 171.5, 114.9, 113.7, 85.12, 80.21, 77.28, 73.27, 53.44,
to 2:1, v/v) gave ketone 6p as a colorless syrup (0.24 g, 97%):
1
[R]23 ) +38.5 (c 1.7, CHCl3); IR (NaCl) 3530, 1750 cm-1; H
D
NMR δ 5.09 (dd, J ) 8.1, 1.2 Hz, 1H), 5.01 (ddd, J ) 10.6, 8.1,
4.8 Hz, 1H), 4.55 (s, 1H), 2.15 (dd, J ) 14.1, 4.8 Hz, 1H), 2.03
(br s, 1H, OH), 1.73 (q, J ) 7.5 Hz, 2H), 1.66 (qd, J ) 7.5, 2.7
Hz, 2H), 1.61 (s, 3H), 1.43 (s, 3H), 1.36 (dd, J ) 14.1, 10.6 Hz,
1H), 1.26 (s, 3H), 1.12 (s, 3H), 0.93 (t, J ) 7.5 Hz, 3H), 0.90 (t,
J ) 7.5 Hz, 3H); 13C NMR δ 204.6, 114.2, 112.0, 91.25, 79.80,
78.05, 73.65, 72.28, 36.69, 29.31, 28.75, 27.42, 26.65, 26.36,