D. C. Harrowven et al. / Tetrahedron 57 02001) 9157±9162
9161
1.6 M solution in THF, 1.55 mmol). After 15 min, HMPA
(1 mL) was added, the mixture was cooled to 2788C, then
allyl bromide (0.186 g, 0.13 mL, 1.54 mmol) was added
over 30 s. After 3 h the mixture was warmed to ambient
temperature over 1 h then quenched with saturated aqueous
ammonium chloride (10 mL). The phases were separated
and the aqueous phase extracted with ether (2£10 mL).
The combined organic phases were washed with water
(10 mL) and brine (10 mL) then dried (MgSO4), ®ltered
and concentrated in vacuo to yellow oil. Puri®cation by
column chromatography (silica, 2% ether in petrol) gave
21 (0.273 g, 1.33 mmol, 90%) as a colourless oil; IR
(neat, cm21) nmax 2932s, 2865m, 1733vs, 1639w, 1459m,
1.1.9.
rel-ꢀ3aR,3bS,6aR,7aR)-2,2,3b-Trimethyl-2,3,3a,
3b,4,6a,7,7a-octahydro-1H-cyclopenta[a]pentalen-6a-ol
[22]. A solution of diene 6 (0.160 g, 0.684 mmol) and
Grubbs' catalyst (31.6 mg, 0.038 mmol) in dichloromethane
(10 mL) was heated at 408C with under argon for 5 h. The
mixture was then concentrated in vacuo and puri®ed by
column chromatography (silica, 5±20% ether in petrol) to
give 22 (0.116 g, 0.604 mmol, 88%) as a colourless oil; IR
(neat, cm21) nmax 3500±3300 brm, 2933m, 2863w, 1463w,
1363m, 1277w, 1077s, 1009vs, 770m, 732s; 1H NMR
(300 MHz, CDCl3) dH 5.79 (1H, app. dt, J5.6, 2.4 Hz,
CHvCHCH2), 5.58 (1H, app. dt, J5.6, 2.1 Hz,
CHvCHCH2), 2.29 (2H, app. t, J2.2 Hz, CH2CHv),
2.32±2.12 (3H, m), 1.65±1.50 (2H, m), 1.50±1.32 (3H,
m), 1.19 (1H, dd, J12.8, 4.6 Hz), 1.08 (3H, s, CH3), 0.99
(3H, s, CH3), 0.90 (3H, s, CH3); 13C NMR (75 MHz, CDCl3)
dC 136.6 (vCH), 132.8 (vCH), 95.1 (COH), 56.6 (CH),
50.2 (CH2), 50.1 (C), 47.3 (CH2), 45.6 (CH2), 42.9 (CH2),
41.4 (C), 40.2 (CH), 30.8 (CH3), 29.1 (CH3), 19.5 (CH3);
LRMS (CI) m/z 206 (M1 and/or [M1NH42H2O]1, 22%),
189 ([MH2H2O]1, 12%), 96 (100%); HRMS (CI) m/z
Found [M1NH42H2O]1: 206.1914. C14H22N requires
206.1909.
1
1409m, 1374m, 1366w, 994m, 913s; H NMR (300 MHz,
CDCl3) dH 5.70 (1H, ddt, J17.3, 9.9, 7.4 Hz, vCH), 5.10±
4.99 (2H, m, vCH2), 2.80±2.55 (3H, m), 2.11 (2H, m,
CH2CHv), 1.95±1.85 (2H, m), 1.44 (1H, ddd, J12.5,
6.8, 1.5 Hz), 1.20 (1H, dd, J13.2, 4.6 Hz), 1.11 (1H,
app. t, J12.5 Hz), 1.06 (3H, s, CH3), 0.97 (3H, s, CH3),
0.95 (3H, s, CH3); 13C NMR (75 MHz, CDCl3) dC 222.8
(CvO), 133.6 (vCH), 118.4 (vCH2), 52.7 (C), 50.2
(CH), 49.1 (CH2), 44.7 (CH2), 43.8 (CH2), 43.7 (CH2),
40.4 (C), 34.3 (CH), 30.2 (CH3), 28.7 (CH3), 17.5 (CH3);
LRMS (CI) m/z 207 ([MH]1, 100%), 206 (M1, 70%), 149
(50%), 123 (100%); HRMS (ES) m/z Found [MH]1:
207.1747. C14H23O requires 207.1749.
1.1.10. rel-ꢀ3aR,3bS,7aR)-2,2,3b-Trimethyl-2,3,3a,4,5,7,7a-
octahydro-1H-cyclopenta[a]pentalen-5-one [5]. To
a
solution of the allyl alcohol 22 (49 mg, 0.238 mmol) in
dichloromethane (5 mL) was added PCC on alumina
(0.55 gof ca. 20% wt on alumina, 0.510 mmol) at ambient
temperature under argon. After 24 h the reaction mixture
was poured onto a pre-loaded silica chromatography
column and eluted (20±50% ether in petrol) to give 5
(31 mg, 0.152 mmol, 64%) as a colourless oil; IR (neat,
cm21) nmax 2951w, 2866w, 1708vs, 1633m, 1465w,
1.1.8. rel-ꢀ1S,2R,3aR,6aR)-1-Allyl-1,5,5-trimethyl-2-vinyl-
perhydro-2-pentalenol [6]. Cerium trichloride hepta-
hydrate (3.36 g, 9.56 mmol) was warmed to 1408C under
high vacuum with stirring for 150 min. The resulting
white powder was cooled under argon, suspended in THF
(20 mL), and sonicated for 30 min. After coolingto 0 8C a
solution of ketone 21 (0.197 g, 0.956 mmol) in THF (5 mL)
was added followed by vinylmagnesium chloride (5.56 mL
of a 1.72 M solution in THF, 9.56 mmol). After 2 h the
mixture was warmed to ambient temperature over 30 min.
After 16 h the mixture was poured onto 2 M HCl (50 mL)
then extracted with ether (3£15 mL). The combined organic
phases were washed with brine (25 mL) then dried
(MgSO4), ®ltered and concentrated in vacuo to yellow oil.
Puri®cation by column chromatography (silica, 4% ether in
petrol) gave 6 (0.157 g, 0.671 mmol, 70%) as a colourless
oil; IR (neat, cm21) nmax 3600±3400w, 2950m, 2864w,
1
1366w, 1223w, 1151w, 909w, 843w; H NMR (300 MHz,
CDCl3) dH 5.68 (1H, d, J1.9 Hz, vCH), 2.85±2.74 (2H,
m), 2.44±2.20 (4H, m), 1.79 (1H, ddd, J12.2, 7.2, 1.6 Hz,
CH), 1.53 (1H, ddd, J12.9, 8.7, 1.6 Hz), 1.45 (1H, dd, J
12.9, 8.5 Hz), 1.25±1.15 (1H, m), 1.10 (3H, s, CH3), 1.08
(3H, s, CH3), 0.95 (3H, s, CH3); 13C NMR (75 MHz, CDCl3)
dC 211.1 (CvO), 196.0 (vC), 122.2 (vCH), 52.9
(CH2CvO), 50.7 (CH), 49.7 (CH2), 49.5 (C), 44.6 (CH),
44.0 (C), 40.5 (CH2), 33.1 (CH2), 29.2 (CH3), 27.6 (CH3),
24.8 (CH3); LRMS (CI) m/z 205 ([MH]1, 100%); HRMS
(CI) m/z Found [MH]1: 205.1590. C14H21O requires
205.1592.
1
1637w, 1463w, 1376w, 997m, 913s; H NMR (300 MHz,
CDCl3) dH 6.03 (1H, dd, J17.4, 10.8 Hz, vCHC), 5.80
(1H, ddt, J17.7, 10.3, 7.4 Hz, vCHCH2), 5.25 (1H, dd,
J17.4, 1.6 Hz, CHHvCHC), 5.11 (1H, dd, J10.8,
1.6 Hz, CHHvCHC), 5.05±4.93 (2H, m, CH2vCHCH2),
2.62±2.50 (2H, m, 2£CH), 2.11 (1H, app. dd, J13.4,
9.3 Hz, CHH), 2.00±1.85 (2H, m, 2£CH2CHv), 1.74±
1.62 (2H, m, 2£CHH), 1.53 (1H, dd, J13.4, 3.8 Hz,
CHH), 1.39±1.25 (3H, m, 2£CHH1OH), 1.05 (3H, s,
CH3), 0.90 (6H, app. s, C(CH3)2); these assignments were
1.1.11. rel-ꢀ3aR,3bS,7aR)-2,2,3b-Trimethyl-4-methylene-
2,3,3a,3b,4,5,7,7a-octahydro-1H-cyclopenta[a]penta-len-
5-one [23]. Prepared usingthe procedure of Greene et al.
13
Thus, enone 5 (29 mg, 0.142 mmol) in THF (2 mL) at
2788C and under argon was treated with LiHMDS
(0.28 mL of a 1 M solution in THF, 0.28 mmol). The reac-
tion was warmed to 2358C over 1 h, then methyl formate
(34 mg, 0.035 mL, 0.568 mmol) was added. The mixture
was warmed to ambient temperature over 45 min then
cooled to 2788C and treated with a second portion of
LiHMDS (0.66 mL of a 1 M solution in THF, 0.66 mmol).
After warmingto 2358C over 1 h, methyl formate (0.345 g,
0.354 mL, 5.76 mmol) was added and the mixture warmed
to ambient temperature. 1 M HCl (5 mL) was added and the
mixture extracted into dichloromethane (3£10 mL). The
combined organic phases were dried (MgSO4), ®ltered and
1
established by H±1H COSY; 13C NMR (75 MHz, CDCl3)
dC 144.0 (vCH), 138.3 (vCH), 119.0 (vCH2), 114.8
(vCH2), 89.7 (COH), 52.8 (CH), 51.7 (CH2), 51.5 (C),
46.6 (CH2), 45.8 (CH2), 45.4 (CH2), 44.1 (C), 41.1 (CH),
31.1 (CH3), 29.0 (CH3), 18.0 (CH3); LRMS (CI) m/z 235
([MH]1, 10%), 217 ([MH2H2O]1, 76%), 177 (100%);
HRMS (ES) m/z Found [M1Na]1: 257.1879. C16H26NaO
requires 257.1881; Found [MH2H2O]1: 217.1955. C16H25
requires 217.1956.