8332
J. Robertson et al. / Tetrahedron 56 (2000) 8321±8333
yl)-4-silacyclohexanol (40) (9 mg, 13%) as colourless oils.
Data for 39: Rf 0.51 (1:1 petrol/ether); Accurate mass:
Found 334.2566, C20H36NOSi (MNH14 ) requires
334.25660; nmax/cm21 3384m, 3058m, 3022m, 2931s,
2865s, 1599s, 1494s, 1383s, 1112s, 880s, 774s, 698s,
668s; dH (500 MHz, CDCl3) 0.56 (3H, d, J7.4 Hz, Si(CH-
MeMe)), 0.73 (1H, app. t, J13.9 Hz, SiCHeqHax), 0.85±
0.95 (9H, m, SiCHeqHax, Sii-Pr and Si(CHMe2)), 0.96 (3H,
d, J7.4 Hz, Si(CHMeMe), 1.79 (3H, s, CH3Cv), 2.03
(1H, br s, OH), 2.15 (1H, ddd, J13.7, 13.1, 11.4 Hz,
CHeqHaxCHOH), 2.27 (1H, ddd, J13.9, 9.2, 3.3 Hz,
CHCv), 2.38 (1H, app. dt, J13.1, 2.8 Hz,
CHeqHaxCHOH), 2.51 (1H, dd, J13.7, 2.8 Hz, CHPh),
3.49 (1H, ddd, J11.4, 9.2, 2.8 Hz, CHOH), 4.92 (1H,
app. s, vCHH), 4.92 (1H, d, J1.7 Hz, vCHH), 7.11±
7.25 (5H, m, Ph); dC (125 MHz, CDCl3) 9.1, 9.2, 9.9,
17.9, 18.0 (two peaks), 18.3, 18.8, 29.3, 37.9, 51.7, 72.4,
112.5, 124.4, 126.4, 128.3, 144.0, 149.0; m/z (CI) 334
(MNH14 , 9%), 317 (MH1, 3), 299 (37), 273 (16), 148
(100). Data for 40: Rf 0.63 (1:1 petrol/ether); Accurate
mass: Found 334.2566, C20H36NSiO (MNH14 ) requires
334.25660; nmax/cm21 3466m, 3076m, 3013m, 2940s,
2865 s, 1600s, 1495s, 1463s, 1260s, 1084s, 1017s, 798s,
699s, 666s; dH (500 MHz, CDCl3) 0.58±1.2 (16H, m,
SiCH2 and 2£i-Pr), 1.87 (3H, s, CH3Cv), 2.24 (1H, ddd,
J14.1, 13.9, 1.6 Hz, CHeqHaxCHOH), 2.32 (1H, d,
J13.6 Hz, CHCv), 2.42 (1H, dd, J13.9, 4.2 Hz,
CHeqHaxCHOH), 2.86 (1H, dd, J14.1, 4.2 Hz, CHPh),
4.17 (1H, app. d, J4.1 Hz, CHOH), 5.00 (2H, s, vCH2),
7.12±7.24 (5H, m, Ph); dC (125 MHz, CDCl3) 9.1, 9.5, 14.1,
17.9, 18.0, 18.3, 18.6, 19.2, 26.8, 36.0, 46.6, 68.3, 110.9,
124.2, 126.8, 128.1, 144.7, 149.9; m/z (CI) 334 (MNH14 ,
53%), 317 (MH1, 3), 299 (17), 273 (39), 148 (100), 131
(27), 117 (19).
4,4-Diisopropyl-7-methyl-2-phenyl-4-silaoct-6-enal (43).
To a cooled (08C) mixture of alcohol 42 (46 mg,
3
0.15 mmol) and MS4 A (150 mg) in DCM (0.85 cm ) was
Ê
added PDC (83 mg, 0.22 mmol). The reaction mixture was
allowed to warm to rt then stirred for 6 h. The mixture
was diluted with ether (5 cm3) and ®ltered through Celitew,
the Celitew being washed thoroughly with ether and the
combined ®ltrates concentrated in vacuo to give a pale
pink oil. Puri®cation by chromatography (10:1 petrol/
ether) gave the aldehyde 43 as a colourless oil (24 mg,
53%). Rf 0.65 (1:1 petrol/ether); Accurate mass: Found
334.2566, C20H36NOSi (MNH14 ) requires 334.25660; nmax
/cm21 3428w, 3062m, 3028m, 2941s, 2888s, 2885s, 2714m,
1727s, 1664s, 1600m, 1581m, 1492m, 1453s, 882s, 819s,
736s, 700s; dH (400 MHz, CDCl3) 0.82±1.06 (14H, m,
2£?i-Pr), 1.06±1.12 (1H, m, SiCHHCHPh), 1.34 (1H, app.
dd, J8.2, 3.4 Hz, SiCHHCHv), 1.46 (1H, dd, J15.1,
6 Hz, SiCHHCHPh), 1.51±1.54 (1H, m, SiCHHCHv),
1.55 (3H, s, CH3Cv), 1.65 (3H, d, J1 Hz, CH3Cv),
3.63 (1H, ca. td, J6, 2.6 Hz, PhCH), 5.05 (1H, br t
J8.2 Hz, CHv), 7.22±7.93 (5H, m, Ph), 9.59 (1H, d,
J2.6 Hz, CHO); dC (100.6 MHz, CDCl3) 10.2, 11.6,
11.8, 11.9, 17.6, 17.9, 18.1, 18.2, 25.8, 30.9, 54.8, 119.9,
127.6, 128.8, 129.0, 138.2, 142.5, 200.4; m/z (CI) 334
(MNH14 , 15%), 317 (MH1, 7), 247 (100), 148 (75), 117
(21).
Treatment of aldehyde (43) with dimethylaluminium
chloride. To
a solution of aldehyde 43 (24 mg,
0.076 mmol) in DCM (5 cm3) at rt was added dropwise
dimethylaluminium chloride (114 ml of a 1 M solution in
hexanes, 0.114 mmol). After 30 min 1 M aqueous sodium
hydroxide solution (3 cm3) was added and the mixture
stirred vigorously for 10 min. Water (5 cm3) was added to
the separated aqueous layer, which was then extracted with
ether (2£3 cm3). The combined organic portions were
washed with brine (5 cm3), then dried (magnesium sulfate)
and concentrated in vacuo. Puri®cation by chromatography
(10:1 petrol/ether) gave trans, trans-4,4-diisopropyl-2-
phenyl-6-(propen-2-yl)-4-silacyclohexanol (44) (12 mg,
50%) and cis, cis-diisopropyl-2-phenyl-6-(propen-2-yl)-4-
silacyclohexanol (45) (2 mg, 8.5%) as colourless oils.
Data for 44: Rf 0.65 (1:1 petrol/ether); Accurate mass:
Found 334.2566, C20H32SiNO (MNH14 ) requires
334.25660; nmax /cm21 3500m, 2939s, 2863s, 1343s,
1124s, 1013s, 882s, 780s, 698s; dH (400 MHz, CDCl3)
0.86±1.01 (4H, m, 2£SiCH2), 1.03±1.10 and 1.24±1.38
(14H, m, 2£i-Pr), 1.83 (3H, s, CH3Cv), 2.53 (1H, dd,
J13.7, 9.9 Hz, CH(Cv)), 2.85 (1H, ddd, J13.4, 9.9,
3.5 Hz, CHPh), 3.54 (1H, br t, J9.9 Hz, CHOH), 4.87
(1H, s, vCHH), 4.90 (1H, s, vCHH), 7.27±7.40 (5H, m,
Ph); dC (100.6 MHz, CDCl3) 10.5, 11.0, 12.4, 16.3, 17.7,
18.3, 18.4, 49.3, 51.5, 75.4, 111.7, 126.4, 127.2, 128.6,
147.0, 149.8; m/z (CI) 334 (MNH14 , 30%), 317 (MH1, 8)
247 (43), 148 (100), 131 (21), 117 (18). Data for 45: Rf 0.67
(1:1 petrol: ether); Accurate mass: Found 334.2566,
4,4-Diisopropyl-7-methyl-2-phenyl-4-silaoct-6-en-1-ol
(42). A solution of tributylprenylstannane26 (470 mg,
1.31 mmol) in THF (3 cm3) was cooled to 2788C then
methyllithium (1.87 cm3 of a 0.77 M solution in ether,
1.44 mmol) was added dropwise and the mixture was stirred
at 2788C for 1 h. A solution of crude oxasilacyclopentane
41 (650 mg, 2.62 mmol) in THF (3 cm3) was added drop-
wise, the reaction mixture was allowed to warm up to rt and
then stirred for 19 h. Water (2 cm3) was added and the
organic product was extracted with ether (3£2 cm3). The
organic portions were combined, washed with brine
(2.5 cm3), dried (magnesium sulfate) and the solvent
removed in vacuo. Puri®cation by chromatography (5:1
petrol/ether) afforded the alcohol 42 as a colourless oil
(107 mg, 26% from tributylprenylstannane). Rf 0.37 (1:1
petrol/ether);
Accurate
mass:
Found
336.2723,
C20H38NSiO (MNH14 ) requires 336.27225; nmax/cm21
3364m, 3028m, 2941s, 2865s, 1602m, 1494s, 1463s,
1383s, 1098s, 1053s, 1015s, 883s, 762s; dH (400 MHz,
CDCl3) 0.80±1.12 (15H, m, CHHSi(i-Pr)2), 1.22±1.38
(3H, m, CHHSiCH2), 1.54 (3H, s, CH3Cv), 1.64 (3H, d,
J0.7 Hz, CH3Cv), 2.94 (1H, app. tt, J8.5, 5.7 Hz,
CHPh), 3.63 (1H, dd, J10.6, 8.5 Hz, CHHOH), 3.70
(1H, dd, J10.6, 5.7 Hz, CHHOH), 5.02 (1H, br t, J
8.3 Hz, CHv), 7.22±7.35 (5H, m, Ph); dC (100.6 MHz,
CDCl3) 11.6, 11.8, 12.1, 13.1, 17.6, 18.1, 18.2, 18.3, 25.8,
44.2, 70.3, 120.3, 126.9, 128.1, 128.6, 144.0; m/z (CI) 336
(MNH14 , 11%), 202 (59), 148 (100), 58 (15).
C20H32SiNO (MNH14 ) requires 334.25660;
n
max/cm21
3500w, 2924s, 2865s, 1458s, 886s, 792s, 750s, 698s; dH
(400 MHz, CDCl3) 0.90±0.99 and 1.29±1.38 (14H, m,
2£i-Pr), 1.04±1.16 (4H, m, 2£SiCH2), 1.85 (3H, s,
vCCH3), 2.53 (1H, dd, J11.5, 4 Hz, CH(Cv)), 2.80
(1H, ddd, J11.8, 6.8, 2 Hz, CHPh), 3.91 (1H, ca. dd,
J6.8, 4 Hz, CHOH), 5.10 (1H, s, vCHH), 5.11 (1H, s,