(40 mg, 0.09 mmol) as an oil (10 mg, 51%), from 13 (100 mg,
0.29 mmol) as an oil (38 mg, 58%) and by method B from 14
(100 mg, 0.29 mmol) as an oil (27 mg, 42%); Rf(Et2O–hexane,
(2SR,3RS )-2-[1ЈRS-Dimethyl(phenyl)silylbenzyl]butane-
1,3-diol
Similarly, the ester 13 (70 mg, 0.21 mmol) gave the diol as an oil
(47 mg, 73%); νmax(film)/cmϪ1 3358 (OH), 2967 (CH) and 1598
(Ar); δH(400 MHz; CDCl3) 7.53 (2 H, m, m-ArH ), 7.36–7.35
(3 H, m, o- and p-ArH ), 7.23 (2 H, t, J 6.0, m-ArH ), 7.11 (1 H,
tt, J 6.0 and 1.0, p-ArCH ), 7.04 (2 H, br d, J 5.5, o-ArCH ), 4.07
(1 H, br dt, J 12.0 and 2.5, CHAHBOH), 3.76 (1 H, ddd, J 12.0,
6.0 and 2.5, CHAHBOH), 3.70 (1 H, m, MeCHOH), 3.02 (1 H,
d, J 12.0, PhCH ), 2.30 (1 H, br d, J 6.0, MeCHOH ), 1.92 (1 H,
br t, J 3.5, CH2OH ), 1.83 (1 H, dq, J 12.0 and 2.5, CHCH2OH),
1.14 (3 H, d, J 6.5, MeCHOH), 0.33 (3 H, s, SiMeAMeB) and
0.09 (3 H, s, SiMeAMeB); δC(100 MHz; CDCl3) 144.14, 140.26
(ArC), 135.39, 130.78, 130.33, 130.03, 129.59, 126.63 (ArCH),
70.53 (MeCHOH), 63.35 (CH2OH), 47.89 (CHCH2OH), 36.57
(PhCH), 23.51 (MeCHOH), 0.00 (SiMeAMeB) and Ϫ2.91
(SiMeAMeB); m/z (ESI) 337 (MNaϩ, 100%)(Found MNaϩ,
337.1604. C19H26O2Si requires M ϩ Na, 337.1600).
1 : 1) 0.1; νmax(film)/cmϪ1 3398 (OH), 2972 (CH), 1717 (C᎐O),
᎐
1495 (Ar), 1438 (CH) and 1050 (CO); δH(400 MHz; CDCl3)
7.44–7.25 (5 H, m, Ar), 5.17 (1 H, dd, J 7.5 and 4.5, PhCH ),
4.20 (1 H, br sextet, J 6.5, MeCHOH), 3.73 (1 H, d, J 7.5,
PhCHOH ), 3.56 (3 H, s, OMe), 2.84 (1 H, dd, J 6.5 and 4.5,
CHCO), 2.72 (1 H, d, J 5.5, MeCHOH ) and 1.27 (3 H, d, J 6.5,
MeCHOH); δC(100 MHz; CDCl3) 173.77ϩ, 141.19ϩ, 128.11Ϫ,
127.65Ϫ, 125.73Ϫ, 73.83Ϫ, 66.87Ϫ, 58.43Ϫ, 51.39Ϫ and
21.80Ϫ; m/z (ESI) 247 (M ϩ Naϩ, 84%)(Found MNaϩ,
247.0948. C12H16O4 requires M ϩ Na, 247.0946).
Methyl
(4SR,5SR,6RS )-1,1,3,3,6-pentamethyl-4-phenyl-
[1,2,3]oxadisilinane-5-carboxylate 33. By method A from a
14 : 86 mixture of 21 and 23 (127 mg, 0.276 mmol) as a solid
(68 mg, 72%) consisting of a 14 : 86 mixture of disiloxane 33;
δH(400 MHz; CDCl3) 7.20–7.01 (5 H, m, Ar), 3.35 (3 H, s,
OMe), 3.07 (1 H, t, J 12.5, CHCO), 2.50 (1 H, d, J 12.5,
PhCH ), 1.17 (1 H, dq, J 12.5 and 7.5, MeCH ), 0.87 (3 H, d,
J 7.5, MeCH), 0.20 (3 H, s, SiMe), 0.19 (3 H, s, SiMe), 0.15
(3H, s, SiMe) and 0.08 (3 H, s, SiMe); δC(125 MHz; CDCl3)
174.29ϩ, 139.78ϩ, 130.06Ϫ, 128.04Ϫ, 125.08Ϫ, 50.95Ϫ,
49.98Ϫ, 38.63Ϫ, 18.19Ϫ, 13.63Ϫ, 0.42Ϫ, Ϫ0.50Ϫ, Ϫ0.61Ϫ and
Ϫ2.23Ϫ; m/z (ESI) 345 (MNaϩ, 100%), 307 (M – Me, 43%)
and 263 (M Ϫ CO2Me, 63%)(Found MNaϩ, 345.1316.
C16H26O3Si2 requires M ϩ Na, 345.1318), and disiloxane 28
with signals (1H-NMR) identifiable from the sample described
above.
Synthesis of acetonides
Typically, the diol (0.12 mmol), 2,2-dimethoxypropane (0.6
cm3) and toluene-p-sulfonic acid (3 mg) in dimethylformamide
(2 cm3) were stirred at room temperature for 14 h. Ether (30
cm3) and water (30 cm3) were added and the layers separated.
The organic phase was washed with water (2 × 30 cm3) and
brine (30 cm3), dried (Na2SO4), and concentrated under
reduced pressure. Chromatography (SiO2, Et2O–hexane, 1 : 3)
gave the acetonides. The following compounds were prepared
by this method.
Methyl (4RS,5SR,6RS )-2,2,4-trimethyl-6-phenyl[1,3]diox-
ane-5-carboxylate 27. From the diol 26 (30 mg, 0.13 mmol) as a
Methyl
(4SR,5RS,6SR)-1,1,3,3,6-pentamethyl-4-phenyl-
[1,2,3]oxadisilinane-5-carboxylate 34. By Method A, from a 35 :
65 mixture of B and C, separated clean from a 35 : 65 mixture
of disiloxanes 33 and 34, as an oil (7 mg, 36%); δH(400 MHz;
CDCl3) 7.21–7.01 (5 H, m, Ar), 3.53 (1 H, dd, J 13.5 and 2.5,
CHCO), 3.45 (3 H, s, OMe), 2.79 (1 H, d, J 13.5, PhCH ), 1.18
(1 H, qd, J 7.5 and 2.5, MeCH ), 1.12 (3 H, d, J 7.5, MeCH),
0.27 (3 H, s, SiMe), 0.19 (3 H, s, SiMe), 0.17 (3 H, s, SiMe) and
Ϫ0.20 (3 H, s, SiMe); δC(125 MHz; CDCl3) 174.61, 149.03,
141.86, 135.96, 129.74, 129.48, 128.28, 127.09, 124.72, 122.05,
51.27, 45.17, 33.73, 22.14, 9.59, Ϫ0.37, Ϫ0.57, Ϫ1.34 and
Ϫ1.60; m/z (ESI) 345 (M ϩ Naϩ, 100%), 307 (M Ϫ Me, 43%)
solid (26 mg, 74%); νmax(solid)/cmϪ1 2991 (CH), 1747 (C᎐O),
᎐
1609 (MeO), 1575, 1493 (Ar) and 1432 (CH); δH(400 MHz;
CDCl3) 7.52–7.24 (5 H, m, ArCH ), 5.15 (1 H, d, J 3.5, PhCH ),
4.35 (1 H, qd, J 6.5 and 3.0, MeCH ), 3.41 (3 H, s, OMe), 2.68
(1 H, t, J 3.5, CHCO), 1.62 (3 H, s, (CMeAMeB), 1.57 (3H, s,
(CMeAMeB) and 1.26 (3 H, d, J 6.5, MeCH); δC(100 MHz;
CDCl ) 168.39 (C᎐O), 134.95 (ArC), 128.72, 128.46, 127.20,
᎐
3
126.59, 124.48 (ArCH), 98.28 (PhCH), 70.40 (MeCH), 64.63
(OMe), 50.02 (CHCO), 28.75 (MeCH), 18.59 (CMeAMeB) and
18.05 (CMeAMeB); m/z (ESI) 287 (MNaϩ, 81%)(Found MNaϩ,
287.1271).
and 263 (M
–
CO2Me, 63%)(Found MNaϩ, 345.1316.
C16H26O3Si2 requires M ϩ Na, 345.1318).
Methyl (4RS,5RS,6RS )-2,2,4-trimethyl-6-phenyl[1,3]diox-
ane-5-carboxylate 3014. From the diol 29 (6 mg, 0.03 mmol) as
an oil (10 mg, 92% yield adjusted for presence of the plasticiser);
νmax(film)/cmϪ1 2924 (CH) and 1739 (C᎐O); δ (400 MHz;
(2SR,3SR)-2-[1ЈRS-Dimethyl(phenyl)silylbenzyl]butane-
1,3-diol
᎐
H
The ester 12 (80 mg, 0.23 mmol) in anhydrous diethyl ether
(2 cm3) was stirred under nitrogen with lithium aluminium
hydride (10 mg, 0.26 mmol) at 0 ЊC for 3 h. Water (2 cm3) and
hydrochloric acid (1 mol dmϪ3, 5 cm3) were added, and the
mixture was partioned between ether (30 cm3) and water
(20 cm3). The organic phase was washed with brine (20 cm3),
dried (Na2SO4) and concentrated under reduced pressure.
Chromatography (SiO2, Et2O–hexane, 1 : 1) gave the diol as an
oil (37 mg, 50%); νmax(film)/cmϪ1 3374 (OH), 2960 (CH) and
1600 (Ar); δH(400 MHz; CDCl3) 7.46 (2 H, m, m-ArH ), 7.34–
7.32 (3 H, m, p- and o-ArH ), 7.23 (2 H, m, m-Ar CH ), 7.10
(1 H, tt, 7.5 and 2.0, p-ArCH ), 7.02 (1 H, m, o-ArCH ), 3.80
(1 H, dd, J 11.0 and 3.5, CHAHBOH), 3.75 (1 H, qd, J 6.5 and
3.0, MeCHOH), 3.57 (1 H, dd, J 11.0 and 9.5, CHAHBOH),
2.60 (1 H, dtd, J 12.5, 9.0 and 3.5, CHCH2OH), 2.07 (1 H, d,
J 12.0, PhCH ), 1.06 (3 H, d, J 6.5, MeCHOH), 0.35 (3 H, s,
SiMeAMeB) and Ϫ0.14 (3 H, s, SiMeAMeB); δC(125 MHz;
CDCl3) 141.93ϩ, 138.59ϩ, 133.63Ϫ, 129.13Ϫ, 128.50Ϫ,
128.25Ϫ, 127.95Ϫ, 125.10Ϫ, 70.25Ϫ, 64.08ϩ, 46.49Ϫ, 35.85Ϫ,
16.42Ϫ, Ϫ1.25Ϫ and Ϫ5.09Ϫ; m/z (ESI) 337 (MNaϩ,
100%)(Found MNaϩ, 377.1613).
CDCl3)1 7.32–7.25 (5 H, m, ArCH ), 5.01 (1 H, d, J 10.5,
PhCH ), 4.26 (1 H, qd, J 10.0 and 6.0, MeCH ), 3.48 (3 H, s,
OMe), 2.42 (1 H, t, J 10.5, CHCO), 1.50 (3 H, s, (CMeAMeB),
1.42 (3 H, s, (CMeAMeB) and 1.19 (3 H, d, J 6.0, MeCH);
δ (125 MHz; CDCl ) 171.78 (C᎐O), 139.57 (ArC), 131.63,
᎐
C
3
128.50, 128.34, 126.63 (ArCH), 99.25 (CMe2), 73.78 (PhCH),
67.21 (MeCH), 56.50 (OMe), 51.56 (CHCO), 29.91 (MeCH),
20.33 (CMeAMeB) and 19.63 (CMeAMeB); m/z (ESI) 287
(MNaϩ, 50%)(Found MNaϩ, 287.1255).
Methyl (4SR,5SR,6RS )-2,2,4-trimethyl-6-phenyl[1,3]diox-
ane-5-carboxylate 3214. From the diol 31 (27 mg, 0.12 mmol,
derived from the monosilylmonoalcohol 12) as an oil (18 mg,
68%), and from the diol 31 (18 mg, 0.080 mmol, derived from
the mixture of disilyl esters 21 and 22) as an oil (21 mg, 99%);
νmax(film)/cmϪ1 2986 (CH), 1732 (C᎐O), 1490 (Ar), 1379 (Me)
᎐
and 1134 (CO); δH(400 MHz; CDCl3) 7.30–7.29 (4 H, m, Ar),
7.22 (1 H, m, p-CH ), 5.13 (1 H, d, J 7.0, PhCH ), 4.37 (1 H, dq,
J 9.0 and 7.0, MeCH ), 3.13 (1 H, s, OMe), 2.89 (1 H, dd, J 9.0
and 7.0, CHCO), 1.55 (3 H, s, (CMeAMeB), 1.41 (3 H, s,
(CMeAMeB) and 1.26 (3 H, d, J 6.0, MeCH); δC(100 MHz;
O r g . B i o m o l . C h e m . , 2 0 0 3 , 1, 4 0 1 7 – 4 0 2 4
4023