Stannylated Metomidate
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(R)-(þ)-Ethyl 1-[1-(4-iodophenyl)ethyl]-1H-imidazole-5-carboxylate and (R)-(þ)-
Ethyl 1-[1-(3-iodophenyl)ethyl]-1H-imidazole-5-carboxylate (3 and 4, C14H15IN2O2)
A mixture of 0.135 g of 1 (0.55 mmol), 18 drops of acetic acid, 0.280 g of I2 (1.10mmol), 0.284 g of
CF3CO2Ag (1.10 mmol), and 5 cm3 of dry CCl4 was heated at 80ꢁC (bath temperature) for 16h under
Ar and protected against light. When the starting material was consumed (TLC: Et2O:iPr2NH¼ 9:1,
Rf ¼ 0.74 (1), 0.62 (3 and 4)), the mixture was filtered through Celite and washed with 3 ꢅ 10cm3 of
CH2Cl2. The filtrate was washed with aqueous NH3, NaHSO3, and H2O, dried (MgSO4), and con-
centrated under reduced pressure to leave a residue, which was purified by flash chromatography
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(n-hexane:Et2O:iPr2NH¼ 60:30:1) to give 0.143g (70%) of a mixture of 3=4 (p:m ¼ 11:5 by H
NMR) as a colourless oil. The iodides were separated by preparative HPLC. Iodide 3 crystallised
from n-hexane, mp 74–74ꢁC; 1H NMR: ꢁ ¼ 1.29 (t, J ¼ 7.0, CH3CH2), 1.80 (d, J ¼ 7.0, CH3CH), 4.21
(AB part of an ABX3 system, JAB ¼ 11.0, JAX ¼ JBX ¼ 7.0, CH3CH2), 6.26 (q, J ¼ 7.0, CH3CH), 6.86
(d, J ¼ 8.5, 2Harom), 7.61 (d, J ¼ 8.5, 2Harom), 7.72 (s, Hhet), 7.74 (d, J ¼ 1.0, Hhet) ppm; 13C NMR:
ꢁ ¼ 14.2, 22.1, 54.9, 60.5, 93.4, 122.6, 128.0, 137.9, 138.2, 139.4, 141.2, 160.2 ppm; IR: ꢂꢀ¼ 2982,
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1713, 1487, 1472, 1374, 1348, 1216, 1133 cmꢃ1; ½ꢃꢆD ¼ þ76ꢁ cmꢃ2 gꢃ1 (c ¼ 1.12, acetone).
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4: Oil; H NMR: ꢁ ¼ 1.30 (t, J ¼ 7.0, CH3CH2), 1.82 (d, J ¼ 7.0, CH3CH), 4.21 (AB part of an
ABX3 system, JAB ¼ 10.5, JAX ¼ JBX ¼ 7.0, CH3CH2), 6.29 (q, J ¼ 7.0, CH3CH), 7.04 (t, J ¼ 7.5,
Harom), 7.09 (dt, J ¼ 1.5, 7.5, Harom), 7.43 (t, J ¼ 1.5, Harom), 7.60 (dt, J ¼ 1.5, 7.5, Harom), 7.72 (s,
Hhet), 7.77 (d, J ¼ 1.0, Hhet) ppm; 13C NMR: ꢁ ¼ 14.2, 22.1, 54.6, 60.5, 94.7, 122.6, 125.5, 130.5,
135.2, 137.1, 138.2, 139.5, 143.6, 160.2ppm; IR: ꢂꢀ¼ 2979, 2926, 2853, 1711, 1373, 1348, 1215, 1131,
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1108 cmꢃ1; ½ꢃꢆD ¼ þ40.1ꢁ cmꢃ2 gꢃ1 (c ¼ 2.26, acetone).
(ꢂ)-1-(4-Iodophenyl)ethanol ((ꢂ)-8)
A solution of DIBAH (16.45cm3, 24.67 mmol, 1.5M, in toluene) was added dropwise to a stirred mixture
of 5.08 g of 4-iodoacetophenone (20.65mmol) in 50cm3 of dry Et2O at ꢃ78ꢁC under Ar. After stirring
for 2 h at ꢃ78ꢁC, 2 cm3 of MeOH were added and stirring was continued for 30min at room temperature
before 10 cm3 of H2O were added cautiously and 30min later, the formed aluminium hydroxide was
dissolved in 50 cm3 of 2N HCl under cooling with ice. The organic phase was separated, washed with
H2O and a sat. aqu. solution of NaHCO3, dried (MgSO4), and concentrated under reduced pressure. The
crude product was purified by flash chromatography (n-hexane:CH2Cl2 ¼ 1:2, Rf ¼ 0.20) and bulb to
bulb distillation (90–95ꢁC=0.2 mm) to give 3.91 g (86%) of (ꢂ)-8; mp 47–49ꢁC (Ref. [18] 50.5–
51.5ꢁC); 1H NMR: ꢁ ¼ 1.40 (d, J ¼ 6.5, CH3CH), 1.75 (br s, OH), 4.78 (q, J ¼ 6.5, CH3CH), 7.06 (d,
J ¼ 8.5, 2Harom), 7.60 (d, J ¼ 8.5, 2Harom) ppm; 13C NMR: ꢁ ¼ 25.6, 70.3, 93.1, 127.8, 137.9, 145.9ppm.
(ꢂ)-1-(4-Iodophenyl)ethyl acetate ((ꢂ)-9a)
A mixture of 1.70 g of (ꢂ)-8 (6.85 mmol), 3 cm3 of dry pyridine, and 3 cm3 of Ac2O was stirred for 1 h
at 50ꢁC. After cooling, 50 cm3 of CH2Cl2 and 20cm3 of H2O were added and stirring was continued
for 10 min. The organic phase was separated, washed with 25 cm3 of 2N HCl, 25cm3 of H2O, and
25cm3 of a sat. aqu. solution of NaHCO3, dried (MgSO4), and concentrated under reduced pressure.
The residue was purified by bulb to bulb distillation (85–90ꢁC=0.3mm) (Ref. [19] 114ꢁC=1.1 mm) to
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give 1.86g (93%) of (ꢂ)-9a as a colourless liquid; H NMR: ꢁ ¼ 1.48 (d, J ¼ 6.5, CH3CH), 2.05 (s,
CH3CO), 5.78 (q, J ¼ 6.5, CH3CH), 7.08 (d, J ¼ 8.0, 2Harom), 7.65 (d, J ¼ 8.0, 2Harom) ppm; 13C NMR:
ꢁ ¼ 21.3, 22.1, 71.7, 93.3, 128.0, 137.6, 141.4, 170.2ppm.
(ꢂ)-1-(4-Iodophenyl)ethyl chloroacetate ((ꢂ)-9b, C10H10ClIO2)
Dry pyridine (6.0cm3) and 6.2g of (CH2ClCO)2O (36.26mmol) were added to a stirred solution of
5.95g of (ꢂ)-8 (24.0mmol) in 100 cm3 of dry CH2Cl2 at 0ꢁC under Ar. When the reaction was