instead of SEMCl. The crude product was purified by column
chromatography (CHCl3–MeOH 20:1) to give the urea 8f as a
colourless, viscous oil (38 mg, 22%); νmax (CHCl3) 2921, 1675,
1460, 1226, 1097, 671 cmϪ1; δH (400 MHz; CDCl3) 3.34 (s, 3H,
OCH3), 4.79 (s, 2H, NCH2O), 5.00 (s, 2H, NCH2Ar), 6.14 (d,
J 3.1 Hz, 1H, ArH), 6.31 (d, J 3.1 Hz, 1H, ArH), 7.24–7.35 (m,
5H, ArH); δC (100.6 MHz; CDCl3) 47.1, 56.2, 74.4, 110.1,
111.1, 127.78, 127.80, 128.8, 136.7, 153.5 (HRMS m/z Calc. for
C12H14N2O2: M, 218.1055. Found: Mϩ, 218.1059).
1.95 g, 6.00 mmol), imidazole (3.06 g, 45.0 mmol) and
TBDMSCl (2.89 g, 19.2 mmol) in dimethylformamide (DMF;
16 mL) was stirred for 12 h at 60 ЊC. Water (10 mL) was added,
and the mixture was extracted with AcOEt. The organic layer
was dried over anhydrous sodium sulfate and evaporated to give
an oily residue, which was purified by column chromatography
(AcOEt–n-hexane 1:2). This product was the corresponding
silyl ether of 10, a colourless, viscous oil (2.62 g, 99%); νmax
(CHCl3) 2938, 1505, 1246, 1067, 853 cmϪ1; δH (300 MHz;
CDCl3) Ϫ0.05 [s, 3H, Si(CH3)2], 0.06 [s, 3H, Si(CH3)2], 0.90 [s,
9H, Si(CH3)2C(CH3)3], 3.31 (s, 3H, NCH3), 3.79 (s, 3H, OCH3),
5.88 [s, 1H, ArCH(OTBDMS)Ar], 6.84–7.24 (m, 10H, ArH); δC
(100.6 MHz; CDCl3) Ϫ5.1, Ϫ5.0, 18.2, 25.7, 32.1, 55.2, 68.2,
113.6, 126.3, 127.1, 127.6, 129.1, 129.3, 133.3, 135.0, 136.9,
139.4, 158.8 (HRMS m/z Calc. for C24H32N2O2SSi: M,
440.1954. Found: Mϩ, 440.1951).
NBS (144 mg, 0.81 mmol) was added to a solution of the silyl
ether (297 mg, 0.67 mmol) in THF (1 mL) under N2 at 0 ЊC, and
the whole was stirred for 7 h at 0 ЊC. Water (2 mL) was added,
and the mixture was extracted with AcOEt. The organic layer
was dried over anhydrous sodium sulfate and evaporated to give
an oily residue, which was purified by column chromatography
(AcOEt–n-hexane 1:2). Bromide 11 was a pale yellow, viscous
oil (216 mg, 62%); νmax (CHCl3) 2939, 1506, 1245, 1070, 852
cmϪ1; δH (300 MHz; CDCl3) Ϫ0.05 [s, 3H, Si(CH3)2], 0.18 [s,
3H, Si(CH3)2], 0.91 [s, 9H, Si(CH3)2C(CH3)3], 3.32 (s, 3H,
NCH3), 3.79 (s, 3H, OCH3), 6.08 [s, 1H, ArCH(OTBDMS)Ar],
6.86 (d, J 8.9 Hz, 2H, ArH), 7.06–7.25 (m, 7H, ArH); δC (100.6
MHz; CDCl3) Ϫ5.3, Ϫ5.1, 18.1, 25.8, 32.7, 55.3, 67.0, 113.8,
115.6, 126.3, 126.7, 127.9, 129.3, 132.8, 134.1, 134.2, 139.1,
158.8 (HRMS m/z Calc. for C24H31BrN2O2SSi: M, 518.1058.
Found: Mϩ, 518.1060).
A diastereomeric mixture of 1-(prop-1-enyl)-3-[2-(trimethylsilyl)-
ethoxymethyl]-1,3-dihydroimidazol-2-one 8g
A stirred solution of sulfide 6c (R1 = CH᎐CHCH ; 433 mg, 2.00
᎐
3
mmol) and SEMCl (0.53 mL, 3.00 mmol) in AcOEt (2 mL) was
refluxed for 3 h. The solvent was evaporated off to give imid-
azolium salt 7g. A mixture of 7g and aq. K2CO3 (553 mg, 4.00
mmol in 2 mL) was stirred at 80 ЊC for 3 h. After cooling, the
reaction mixture was extracted with AcOEt, and the organic
layer was dried over anhydrous sodium sulfate and evaporated
to give an oily residue. The crude product was purified by
column chromatography (AcOEt–n-hexane 1:1). (Z)-8g:
Colourless, viscous oil (247 mg, 49%); νmax (CHCl3) 2937, 1687,
1450, 1245, 1074, 834, 653 cmϪ1; δH (400 MHz; CDCl3) Ϫ0.04
[s, 9H, Si(CH3)3], 0.90 (t, J 8.2 Hz, 2H, CH2CH2Si), 1.76 (dd,
J 1.7, 7.2 Hz, 3H, CH᎐CHCH ), 3.56 (t, J 8.2 Hz, 2H,
᎐
3
CH2CH2Si), 5.00 (s, 2H, NCH2O), 5.28 (dq, J 8.9, 7.3 Hz, 1H,
CH᎐CHCH ), 6.37 (d, J 3.1 Hz, 1H, ArH), 6.40 (dq, J 9.0, 1.8
᎐
3
Hz, 1H, CH᎐CHCH ), 6.48 (d, J 3.1 Hz, 1H, ArH); δ (100.6
᎐
3
C
MHz; CDCl3) Ϫ1.4, 12.4, 17.9, 66.2, 72.5, 110.5, 111.0, 115.7,
122.1, 152.3 (HRMS m/z Calc. for C12H22N2O2Si: M, 254.1450.
Found: Mϩ, 254.1445).
(E)-8g: Colourless, viscous oil (231 mg, 45%); νmax (CHCl3)
2976, 1687, 1455, 1244, 1079, 834, 651 cmϪ1; δH (400 MHz;
CDCl3) Ϫ0.04 [s, 9H, Si(CH3)3], 0.88 (t, J 8.2 Hz, 2H,
5-[(tert-Butyldimethylsiloxy)-(4-methoxyphenyl)methyl]-4-
{[3,4-dimethoxy-2-(methoxymethoxy)phenyl]hydroxymethyl}-1-
methyl-2-phenylthio-1H-imidazole 13
CH CH Si), 1.74 (dd, J 1.7, 6.6 Hz, 3H, CH᎐CHCH ), 3.54
᎐
2
2
3
(t, J 8.2 Hz, 2H, CH2CH2Si), 4.97 (s, 2H, NCH2O), 5.45 (dq,
A solution of tert-BuLi in n-pentane (1.64 M; 2.8 mL, 4.50
mmol) was added dropwise to a stirred solution of bromide 11
(1.17 g, 2.24 mmol) in diethyl ether (18 mL) under N2 at
Ϫ78 ЊC. Stirring was continued for 1 h, and a solution of 3,4-
dimethoxy-2-(methoxymethoxy)benzaldehyde 12 (1.09 g, 4.50
mmol) in diethyl ether (6 mL) was added dropwise at Ϫ78 ЊC.
Stirring was continued for 3 h at Ϫ78 ЊC, water (20 mL) was
added, and the mixture was extracted with AcOEt. The organic
layer was dried over anhydrous sodium sulfate and evaporated
to give an oily residue, which was purified by column chrom-
atography (AcOEt–n-hexane 1:2) to give title compound 13, a
diastereomeric mixture (≈4:3), as a pale yellow, viscous oil
(1.15 g, 77%); νmax (CHCl3) 3400, 2925, 2842, 1604, 1505, 1454,
1278, 1244, 1164, 1064, 988, 854 cmϪ1; δH (300 MHz; CDCl3)
of the major isomer: Ϫ0.35 [s, 3H, Si(CH3)2], Ϫ0.07 [s, 3H,
Si(CH3)2], 0.84 [s, 9H, Si(CH3)2(CH3)3], 3.34 (s, 3H, NCH3),
3.55 (s, 3H, OCH3), 3.78 (s, 3H, OCH3), 3.81 (s, 3H, OCH3),
3.85 (s, 3H, OCH3), 5.21 (d, J 15.1 Hz, 1H, OCH2O), 5.23 (d,
J 15.1 Hz, 1H, OCH2O), 6.30 [s, 1H, ArCH(OTBDMS)Ar],
6.34 [d, J 5.9 Hz, 1H, ArCH(OH)Ar], 6.62–7.24 (m, 11H, ArH)
(HRMS m/z Calc. for C35H46N2O7SSi: M, 666.2795. Found:
Mϩ, 666.2791).
J 14.3, 6.8 Hz, 1H, CH᎐CHCH ), 6.35 (d, J 3.1 Hz, 1H, ArH),
6.43 (d, J 3.1 Hz, 1H, ArH), 6.67 (dq, J 14.5, 1.7 Hz, 1H,
᎐
3
CH᎐CHCH ); δ (100.6 MHz; CDCl3) Ϫ1.4, 15.0, 17.8, 66.1,
᎐
3
C
72.4, 107.6, 109.4, 111.4, 122.3, 151.4 (HRMS m/z Calc. for
C12H22N2O2Si: M, 254.1450. Found: Mϩ, 254.1444).
A diastereomeric mixture of 1-benzyl-3-(prop-1-enyl)-1,3-
dihydroimidazol-2-one 8h
Similarly prepared from sulfide 6c as used for the preparation
of 8g except for the use of benzyl bromide (0.36 mL, 3.00
mmol) instead of SEMCl. (Z)-8h: Colourless, viscous oil (168
mg, 39%); νmax (CHCl3) 2975, 1682, 1447, 1229, 672 cmϪ1
;
δH (400 MHz; CDCl ) 1.79 (dd, J 1.8, 7.3 Hz, 3H, CH᎐
᎐
3
CHCH3), 4.80 (s, 2H, NCH2Ar), 5.29 (dq, J 9.0, 7.2 Hz, 1H,
CH᎐CHCH ), 6.17 (d, J 3.1 Hz, 1H, ArH), 6.48 (d, J 3.1 Hz,
᎐
3
1H, ArH), 6.47–6.51 (m, 1H, CH᎐CHCH ), 7.26–7.37 (m, 5H,
᎐
3
ArH); δC (100.6 MHz; CDCl3) 12.4, 47.0, 110.3, 110.6, 114.8,
122.2, 127.77, 127.84, 136.6, 152.2 (HRMS m/z Calc. for
C13H14N2O: M, 214.1106. Found: Mϩ, 214.1111).
(E)-8h: Colourless, viscous oil (153 mg, 36%); νmax (CHCl3)
2977, 1683, 1449, 1237, 647 cmϪ1; δH (400 MHz; CDCl3) 1.78
(dd, J 1.8, 6.8 Hz, 3H, CH᎐CHCH ), 4.79 (s, 2H, NCH Ar),
᎐
3
2
5.47 (dq, J 14.3, 6.8 Hz, 1H, CH᎐CHCH ), 6.15 (d, J 3.1 Hz,
᎐
3
5-Acetoxy-6,7-dimethoxy-9-(4-methoxyphenyl)-1-methyl-2-
phenylthio-1H-naphtho[2,3-d]imidazole 14
1H, ArH), 6.42 (d, J 3.1 Hz, 1H, ArH), 6.74 (dq, J 14.4, 1.6 Hz,
1H, CH᎐CHCH ), 7.24–7.36 (m, 5H, ArH); δ (100.6 MHz;
᎐
3
C
Triethylamine (0.48 mL, 3.43 mmol) and acetic anhydride (0.29
mL, 3.09 mmol) were added dropwise to a solution of alcohol
13 (1.15 g, 1.72 mmol) in CHCl3 (5 mL) under N2 at 0 ЊC, and
the whole was stirred for 3 h at room temperature. Water (4 mL)
was added, and the mixture was extracted with CHCl3. The
organic layer was dried over anhydrous sodium sulfate and
evaporated to give an oily residue, which was purified by
column chromatography (AcOEt–n-hexane 1:2) to give the
CDCl3) 14.9, 46.9, 106.9, 109.0, 111.5, 122.5, 127.72, 127.73,
128.7, 136.5, 151.3 (HRMS m/z Calc. for C13H14N2O: M,
214.1106. Found: Mϩ, 214.1118).
4-Bromo-5-[(tert-butyldimethylsiloxy)-(4-methoxyphenyl)-
methyl]-1-methyl-2-phenylthio-1H-imidazole 11
A mixture of the alcohol 109a (prepared from 6a in 67% yield,
434
J. Chem. Soc., Perkin Trans. 1, 2001, 429–436