Asymmetric Ring-Closing Metathesis
J . Org. Chem., Vol. 63, No. 3, 1998 831
were hydrolyzed (K2CO3 (10 equiv)/MeOH-H2O (2:1), rt, 12 h)
and separated. The dienols were converted to their Mosher
esters to determine the ee ((S)-(+)-MTPACl (1.4 equiv), pyri-
dine, rt 16 h). In both hydrolysis and Mosher ester formation,
reaction completion was confirmed by thin-layer chromatog-
raphy prior to workup.
2H), 1.55 (s, 3H), 1.54 (d, J ) 6.3, 3H), 1.02 (t, J ) 7.9, 9H),
0.62 (q, J ) 7.9, 6H); 13C NMR (75 MHz, C6D6) δ 142.2, 135.7,
118.6, 113.7, 73.9, 37.1, 35.6, 15.8, 13.5, 7.2, 5.4; mass
spectrum (CI, CH4) m/z (relative intensity): 253 (M - H+, 7),
225 (100), 213 (2), 185 (5), 171 (12), 123 (90), 103 (14), 81 (15);
HRMS, m/z calcd for C15H29OSi (M - H+): 253.1988, found:
253.1985.
(b) 12d ,e. In the cases of triethylsiloxy-substituted sub-
strates 12d ,e, unreacted substrates and their cyclized products
were separated by column chromatography. Unreacted 13d ,e
were deprotected (nBu4NF (1.0 equiv)/THF, rt, 1 h) and the
resulting dienols were derived to Mosher esters to determine
the ee ((S)-(+)-MTPACl (1.4 equiv), pyridine, rt, 16 h). In both
deprotection and Mosher ester formation, reaction completion
was confirmed by thin-layer chromatography prior to workup.
Deter m in a tion of Ster eocen ter Con figu r a tion . (R)-
Enriched dienols were prepared according to the kinetic
resolution procedure of Sharpless.23 These alcohols were
converted to the Mosher esters ((S)-(+)-MTPACl (1.4 equiv),
pyridine, rt, 16 h) and compared with the Mosher ester derived
Cyclized P r od u ct 13e. 1-Methyl-3-(triethylsiloxy)cyclo-
pentene (13e): IR (neat) 2955, 2876, 1660, 1456, 1359, 1238,
1156, 1058, 1007, 899, 840, 743 cm-1 1H NMR (300 MHz,
;
C6D6) δ 5.45 (dq, J ) 1.6, 1.6, 1H), 4.87-4.84 (m, 1H), 2.31-
2.19 (m, 1H), 2.19-2.07 (m, 1H), 1.97-1.79 (m, 2H), 1.57 (s,
3H), 1.03 (t, J ) 7.9, 9H), 0.63 (q, J ) 7.9, 6H); 13C NMR (75
MHz, C6D6) δ 143.4, 128.9, 78.3, 35.3, 35.2, 16.7, 7.2, 5.4; mass
spectrum (CI, CH4) m/z (relative intensity): 213 (MH+, 5), 183
(92), 161 (1), 133 (3), 103 (45), 81 (100); HRMS, m/z calcd for
C
12H25OSi (MH+): 213.1675, found: 211.1677.
H yd r olyzed P r od u ct fr om R ecover ed 12g. (R)-(7E)-
1,7-nonadien-6-ol: IR (neat) 3353 (br), 2934, 2859, 1673, 1641,
1
1440, 1064, 994, 966, 910 cm-1; H NMR (300 MHz, C6D6) δ
1
from recovered 12 by H NMR.
5.76 (ddt, J ) 17.1, 10.2, 6.7, 1H), 5.55-5.37 (m, 2H), 5.00
(ddt, J ) 17.1, 1.7, 1.7, 1H), 4.95 (ddt, J ) 10.2, 1.7, 0.9, 1H),
4.00-3.85 (m, 1H), 2.70 (s, 1H), 1.98 (dt, J ) 6.7, 6.7, 2H),
1.54 (d, J ) 5.6, 3H), 1.54-1.30 (m, 4H); 13C NMR (75 MHz,
C6D6) δ 139.0, 135.4, 125.5, 114.7, 72.7, 37.2, 34.1, 25.2, 17.1;
mass spectrum (CI, NH3) m/z (relative intensity): 140 (M+,
Hyd r olyzed P r od u ct fr om Recover ed 12a . (S)-(6E)-6-
Methyl-1,6-octadien-5-ol: IR (neat) 3353 (br), 2936, 1671, 1641,
1445, 1381, 1303, 1056, 1004, 910, 829 cm-1 1H NMR (300
;
MHz, C6D6) δ 5.79 (ddt, J ) 17.1, 10.3, 6.6, 1H), 5.34 (qq, J )
6.6, 1.1, 1H), 5.04 (ddt, J ) 17.1, 2.0, 2.0, 1H), 4.96 (ddt, J )
10.3, 2.0, 1.3, 1H), 3.87 (t, J ) 6.6, 1H), 2.15 (s, 1H), 2.20-
1.94 (m, 2H), 1.72-1.48 (m, 2H), 1.51 (dd, J ) 1.1, 1.1, 3H),
1.49 (d, J ) 6.6, 3H); 13C NMR (75 MHz, C6D6) δ 138.9, 138.6,
120.1, 114.6, 77.2, 34.5, 30.6, 13.0, 11.0; mass spectrum (CI,
NH3) m/z (relative intensity): 158 (MNH4+, 3), 140 (82), 123
(100), 98 (2), 81 (4); HRMS, m/z calcd for C9H20NO (MNH4+):
158.1545, found: 158.1543.
100), 123 (75), 98 (2), 81 (10); HRMS, m/z calcd for C9H16
O
(M+): 140.1201, found: 140.1207.
H yd r olyzed P r od u ct fr om Cyclized P r od u ct 13g.
2-Cycloh exen -1-ol: 1H NMR (300 MHz, C6D6) δ 5.70-5.62
(m, 1H), 5.61-5.54 (m, 1H), 4.02-3.92 (m, 1H), 1.81-1.39 (m,
5H), 1.38-1.20 (m, 1H), 0.89 (s, 1H). Identical with the
authentic sample.
H yd r olyzed P r od u ct fr om Cyclized P r od u ct 13a .
2-Methyl-2-cyclopenten-1-ol: IR (neat) 3333 (br), 2938, 2855,
Hyd r olyzed P r od u ct fr om Recover ed 12h . (R)-(7E)-
7-Meth yl-1,7-n on a d ien -6-ol: IR (neat) 3353 (br), 2932, 2861,
1
1660, 1454, 1315, 1164, 1054, 1031, 973, 824 cm-1; H NMR
1671, 1641, 1443, 1380, 1317, 995, 909, 829 cm-1 1H NMR
;
(300 MHz, C6D6) δ 5.29 (m, 1H), 4.33 (m, 1H), 2.24-2.11 (m,
1H), 2.10-1.89 (m, 2H), 1.66 (s, 3H), 1.57-1.48 (m, 1H), 0.85
(s, 1H); 13C NMR (75 MHz, C6D6) δ 142.5, 127.3, 79.6, 34.4,
29.9, 13.7; mass spectrum (EI) m/z (relative intensity): 98 (M+,
60), 83 (100), 80 (40), 69 (30), 55 (50), 41 (57); HRMS, m/z calcd
for C6H10O (M+): 98.0732, found: 98.0729.
(300 MHz, C6D6) δ 5.76 (ddt, J ) 17.0, 10.2, 6.7, 1H), 5.36 (q,
J ) 6.6, 1H), 5.01 (ddt, J ) 17.0, 1.6, 1.6, 1H), 4.96 (ddt, J )
10.2, 1.6, 0.8, 1H), 3.87 (dd, J ) 6.7, 5.5, 1H), 2.50 (s, 1H),
1.99 (td, J ) 7.0, 6.7, 2H), 1.60-1.25 (m, 4H), 1.54 (s, 3H),
1.50 (d, J ) 6.6, 3H); 13C NMR (75 MHz, C6D6) δ 139.1, 138.8,
119.9, 114.7, 77.7, 34.8, 34.1, 25.6, 13.1, 11.0; mass spectrum
(CI, NH3) m/z (relative intensity): 155 (MH+, 2), 137 (100),
R ecover ed 12d . (S)-(6E)-6-Methyl-5-(triethylsiloxy)-1,6-
octadiene (12d): IR (neat) 2954, 2877, 1671, 1642, 1456, 1415,
1
1239, 1073, 1005, 910, 742 cm-1; H NMR (300 MHz, C6D6) δ
111 (2), 95 (7), 81 (12), 69 (2); HRMS, m/z calcd for C10H19
O
(MH+): 155.1436, found: 155.1438.
5.82 (ddt, J ) 17.0, 10.3, 6.6, 1H), 5.37 (qq, J ) 6.6, 0.8, 1H),
5.07 (ddt, J ) 17.0, 1.9, 1.9, 1H), 4.98 (ddt, J ) 10.3, 1.9, 1.2,
1H), 4.02 (t, J ) 6.6, 1H), 2.20-1.96 (m, 2H), 1.81-1.69 (m,
1H), 1.65-1.55 (m, 1H), 1.58 (dd, J ) 1.1, 1.1, 3H), 1.49 (dd,
J ) 6.7, 0.9, 3H), 1.01 (t, J ) 7.9, 9H,), 0.62 (q, J ) 7.9, 6H,
13C NMR (75 MHz, C6D6) δ 139.0, 138.6, 120.0, 114.6, 78.3,
35.9, 30.5, 13.0, 10.8, 7.2, 5.3; mass spectrum (CI, CH4) m/z
(relative intensity): 253 (M-H+, 10), 225 (100), 199 (65), 123
(65), 103 (17), 81 (9); HRMS, m/z calcd for C15H29OSi (M -
H+): 253.1988, found: 253.1990.
H yd r olyzed P r od u ct fr om Cyclized P r od u ct 13h .
2-Meth yl-2-cycloh exen -1-ol: IR (neat) 3354 (br), 2934, 1454,
1
1434, 1286, 1051, 960, 727 cm-1; H NMR (300 MHz, C6D6) δ
5.34 (s, 1H), 3.74 (m, 1H), 1.89-1.64 (m, 2H), 1.71 (s, 3H),
1.60-1.40 (m, 3H), 1.38-1.25 (m, 1H), 0.84 (s, 1H); 13C NMR
(75 MHz, C6D6) δ 136.1, 124.7, 68.2, 32.7, 25.7, 20.8, 18.7; mass
spectrum (EI) m/z (relative intensity): 112 (M+, 70), 97 (100),
84 (55), 83 (50), 69 (67), 55 (57), 43 (50), 41 (60); HRMS, m/z
calcd for C7H12O (M+): 112.0888, found: 112.0890.
4-Meth yl-4-p en ten -1-ol (16). To a solution of (1-methyl-
vinyl)lithium24 in ether (0.83 M, 100 mL, 83 mmol), was aded
oxetane (4.6 g, 80 mmol) at -78 °C under argon. To the
stirring reaction mixture was added BF3OEt2 (11.8 g, 83 mmol)
dropwise. The reaction was exothermic. The reaction mixture
was stirred for 5 min, and then saturated NaHCO3 aqueous
solution was added to quench the reaction. After addition of
aqueous hydrochloric acid to the reaction mixture, it was
extracted with ether (150 mL × 3). The ether extracts were
dried over MgSO4 and concentrated in vacuo. Flash chroma-
tography (EM reagents silica gel 60, 230-400 mesh, hexane
to hexane/EtOAc ) 5/1) yielded 4.8 g (60%) of 16 as colorless
oil.
Cyclized P r od u ct 13d . 1-Methyl-5-(triethylsiloxy)cyclo-
pentene (13d): IR (neat) 2956, 2877, 1456, 1353, 1239, 1086,
1004, 994, 743 cm-1; 1H NMR (300 MHz, C6D6) δ 5.36 (m, 1H),
4.54-4.50 (m, 1H), 2.36-2.22 (m, 1H), 2.14-1.95 (m, 2H), 1.75
(s, 3H), 1.75-1.69 (m, 1H), 1.01 (t, J ) 7.9, 9H), 0.61 (q, J )
7.9, 6H); 13C NMR (75 MHz, C6D6) δ 142.7, 126.5, 79.9, 35.0,
30.0, 14.0, 7.2, 5.3; mass spectrum (CI, CH4) m/z (relative
intensity): 211 (M - H+, 20), 183 (100), 161 (5), 115 (15), 103
(62), 81 (92); HRMS, m/z calcd for C12H23OSi (M - H+):
211.1518, found: 211.1512.
Recover ed 12e. (S)-(6E)-6-Methyl-3-(triethylsiloxy)-1,6-
octadiene (12e): IR (neat) 2954, 2877, 1671, 1645, 1456, 1416,
1
1239, 1089, 1007, 920, 743 cm-1; H NMR (300 MHz, C6D6) δ
4-Meth yl-4-p en ten -1-ol (16): 1H NMR (300 MHz, C6D6)
d 4.80 (s, 2H), 3.75 (t, 2H, J ) 6.8), 1.95 (t, J ) 6.7, 2H), 1.65
(s, 3H), 1.50 (tt, J ) 6.8, 6.7, 2H), 1.15 (br s, 1H).
5.81 (ddd, J ) 16.7, 10.3, 6.1, 1H), 5.34-5.23 (m, 1H), 5.15
(ddd, J ) 16.7, 1.1, 0.6, 1H), 4.96 (ddd, J ) 10.3, 0.6, 0.6, 1H),
4.07 (dt, J ) 6.1, 6.1, 1H), 2.21-2.01 (m, 2H), 1.79-1.57 (m,
5-Iod o-2-m eth yl-1-p en ta n e (17). To 16 (3.6 g, 36 mmol)
in pyridine (80 mL), was added tosyl chloride (15 g, 79 mmol)
(23) (a) Martin, V. S.; Woodard, S. S.; Katsuki, T.; Yamada, Y.;
Ikeda, M.; Sharpless, K. B. J . Am. Chem. Soc. 1981, 103, 6237-6240.
(b) Catalytic Asymmetric Synthesis; Ojima, I., Ed.; VCH: New York,
1993; chapter 4.1.
(24) Prepared from 2-bromopropene and lithium dispersion. See
Bates, G. S.; Masamune S. Org. Synth. 55, 103-113.