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S.R. Park et al. / Tetrahedron 65 (2009) 10756–10761
3.1.1. Cobalt(II) (1,5,8,12,15,19,22,26-octaazapentacyclo[24.2.1.15,8.112,
15.119,22] dotriacinta-6,13,20,27-tetraene-29,30,31,32-tetraylidene)-io-
dide 12(II)dmethod A. 1,10,100,1%:3,30,300,3%-Tetrakistrimethylene tet-
raimidazolium tetraiodide (1) (0.999 g, 1.059 mmol)27 and sodium
hydride (2.541 g, 0.106 mol) were washed with hexane (20 ml) and
dried under an argon stream. DMF (50 ml) was added and the reaction
mixture stirred for 18 h. Cobalt(II) chloride hexahydrate (252 mg,
1.059 mmol) was dried by heating to 90 ꢀC while under vacuum for
1 h. The solution of NHC ligand was added to CoCl2$6H2O via cannula
and stirred at room temperature for 2 h, then filtered and the DMF
removed by distillation. The residue was dissolved in hot methanol
and filtered, then the solvent reduced in volume and the resultant
blue precipitate collected. Recrystallisation by slow cooling of a satu-
rated methanol solution afforded 12 as blue needles (174 mg, 22%);
mp (>300 ꢀC, dec); [found: [MꢁI]þ (ESI) 618.1121, C24H32N8I2Co re-
quires [MꢁI]þ 618.1121]; nmax (KBr disc/cmꢁ1) 3078, 2954, 2917, 1561,
1407, 1235, 755; m/z (ESI) 618 ([MꢁI]þ, 45%), 246 (100).
meff(293 K)¼4.9 B.M. electronic spectrum (1ꢂ10ꢁ3 M in MeOH, lmax
hexafluorophosphatedTBAHFP). The solution was put in a two-
compartment cell with the second compartment being filled with
a 50 mM solution of TBAHFP in DMF (10 ml). The mixture was
stirred at ꢁ1.5 V for 18 h. The solution was then added to water
(50 ml) and diethyl ether (50 ml) and then extracted with diethyl
ether (3ꢂ50 ml). The organic layer was washed with brine (50 ml)
and dried over sodium sulfate. The solvent was removed under
reduced pressure. The crude product was purified by flash
chromatography (10% ethyl acetate/petroleum ether) to give the
title compound (15c) as a colourless oil31,32 (0.062 g, 90%); nmax
(neat)/cmꢁ1 2933, 2859, 1602, 1473, 1459, 1345, 1159; dH (400 MHz
CDCl3) 1.29–1.37 (2H, m, CH2), 1.52–1.73 (3H, m, 3H–CH), 1.90–1.93
(1H, m, H–CH), 2.13–2.17 (1H, m, H–CH), 2.26–2.30 (1H, m, H–CH),
3.02 (3H, s, CH3), 3.61 (1H, m, CH), 4.44–4.50 (1H, m, CH), 7.15–7.19
(1H, m, ArH), 7.25–7.31 (2H, m, ArH), 7.45 (1H, d, J 7.9, ArH); dC
(100 MHz, CDCl3) 20.9 (CH2), 22.2 (CH2), 24.7 (CH2), 28.6 (CH2),
38.6 (CH), 40.5 (CH), 64.1 (CH3), 115.6 (CH), 123.6 (CH), 124.2 (CH),
128.0 (CH), 134.8 (C), 141.5 (C); m/z (ESI) 252 (MHþ, 100%), 250
(45%), 186 (15%).
nm(e
dm3 molꢁ1 cmꢁ1)): 323 (3481), 590sh, 624 (1933).
3.1.2. Method B. Cobalt(II) chloride hexahydrate (626 mg,
2.68 mmol) and 1,10,100,1%:3,30,300,3%-tetrakistrimethylene tetrai-
midazolium tetraiodide (1) (2.504 g, 2.65 mmol) were dissolved in
methanol (200 ml) and sodium hydroxide (1.059 g, 26.5 mmol)
added. The solution was heated to reflux for 18 h. The reaction
mixture was cooled and the solvent removed in vacuo. The crude
mixture was recrystallised from water to afford the title compound
12(II) as blue needles (1.185 g, 60%); mp (>300 ꢀC, dec); [found:
[MꢁI]þ (ESI) 618.1121, C24H32N8I2Co requires [MꢁI]þ 618.1121];
nmax (KBr disc/cmꢁ1) 3078, 2954, 2917, 1561, 1407, 1235, 755; m/z
(ESI) 618 ([MꢁI]þ, 45%), 246 (100).
3.3.1. 3-Isopropyl-1-methanesulfonyl-2,3-dihydro-1H-indole
15b. [Found: [MNH4]þ (ESþ) 257.1320, C12H17NO2S requires
[MNH4]þ 257.1318.] nmax (neat)/cmꢁ1 2961, 2932, 2874, 1481,
1459, 1348, 1160; dH (400 MHz, CDCl3) 0.86 (3H, d, J 6.8, CH3), 1.01
(3H, d, J 6.9, CH3), 2.04–2.12 (1H, m, CH), 2.87 (3H, s, CH3) 3.31–
3.36 (1H, m, CH), 3.80–3.84 (1H, m, H–CH), 3.89–3.94 (1H, m,
H–CH), 7.02–7.06 (1H, m, ArH), 7.19–7.23 (2H, m, ArH), 7.40 (1H,
d, J 7.9, ArH); dC (100 MHz, CDCl3) 17.9 (CH3), 20.3 (CH3), 31.7
(CH), 34.6 (CH), 46.2 (CH3), 52.7 (CH2), 113.3 (CH), 123.5 (CH),
125.6 (CH), 128.5 (CH), 133.8 (C), 142.5 (C); m/z (CIþ) 257 (MNH4þ,
100%), 239 (5%).
3.2. Example of reduction using cobalt complex 2dTable 2,
entry 14a, 3-ethyl-1-(methylsulfonyl)indoline (15a)
3.3.2. 3-Isopropyl-1-methanesulfonyl-1H-indole 17b. [Found: [M]þ
(ESþ) 237.0819, C12H15NO2S requires [M]þ 237.0818.] nmax (neat)/
cmꢁ1 3054, 2965, 2932, 2873, 1450, 1362, 1265, 1168; dH (400 MHz,
CDCl3) 1.37 (6H, d, J 6.8, 2ꢂCH3), 3.05 (3H, s, CH3), 3.12–3.19 (1H, m,
CH), 7.19 (1H, s, ArH), 7.30–7.39 (2H, m, ArH), 7.64 (1H, d, J 7.2, ArH),
7.91 (1H, d, J 8.0, ArH); dC (100 MHz, CDCl3) 22.8 (CH3), 25.6 (CH),
40.46 (CH3), 113.5 (CH), 120.4 (CH), 121.1 (CH), 123.3 (CH), 125.0
(CH), 130.3 (C), 130.7 (C), 135.9 (C); m/z (Elþ) 237 (Mþ, 45%), 222
(100%), 158 (50%).
Cobalt complex 12(II) (0.258 g, 3.47ꢂ10ꢁ4 mol) was dissolved in
DMF (25 ml) and added to a freshly prepared sodium amalgam (1%,
10 g). The reaction mixture was stirred for 4 h. The solution of
cobalt(I) complex was added to N-(but-2-enyl)-N-(2-iodophenyl)-
methanesulfonamide (8a) (0.108 g, 3.07ꢂ10ꢁ4 mol) and 1,4-cyclo-
hexadiene (0.137 g, 1.71ꢂ10ꢁ3 mol) after centrifuging. This mixture
was then stirred at 65 ꢀC for 18 h. The reaction mixture was then
added to water (50 ml) and diethyl ether (50 ml) and then extrac-
ted with diethyl ether (3ꢂ50 ml). The organic layer was then
washed with water (100 ml) and dried over MgSO4. The solvent
was removed under reduced pressure. The crude product was pu-
rified by column chromatography (10% ethyl acetate/petroleum
ether) to give the title product (15a)30 as a colourless oil (0.056 g,
81%). [Found: [MNH4]þ (ESI) 243.1169, C11H15NO2S requires
[MNH4]þ 243.3503.] nmax (KBr disc)/cmꢁ1 3016, 2963, 2932, 2876,
1601,1480,1462; dH (400 MHz, CDCl3) 1.08 (3H, t, J 7, CH3),1.61–1.72
(1H, m, H–CH), 1.89–1.99 (1H, m, H–CH), 2.98 (3H, s, CH3), 3.35–
3.42 (1H, m, H–CH), 3.69–3.74 (1H, m, H–CH), 4.13–4.17 (1H, m, CH),
7.10–7.14 (1H, m, ArH), 7.27–7.31 (2H, m, ArH), 7.46–7.49 (1H, m,
ArH); dC (100 MHz, CDCl3) 11.8 (CH3), 28.1 (CH2), 34.9 (CH), 42.1
(CH3), 56.5 (CH2), 114.0 (CH), 124.1 (CH), 125.2 (CH), 128.8 (CH),
135.5 (C), 142.3 (C); m/z (EI) 225 (Mþ, 45%), 196 (50), 146 (78), 130
(79), 118 (100), 91 (35).
3.3.3. X-ray crystallography. Crystals suitable for X-ray diffraction
were obtained by slow cooling of a methanolic solution of 12. Data
were measured on a Nonius kappa CCD diffractometer equipped
graphite monochromated with Mo Ka radiation. The structure was
solved by direct methods using SHELXS-8633 in the WinGX suite of
34
programs.
C
H32Co1I2N8$0.5CH3OH, Mr¼759.32, deep blue needle,
24
0.40ꢂ0.20ꢂ0.15 mm, a¼6.7987(1), b¼11.0938(3), c¼19.2961(5) Å,
V¼1455.38(6) Å3, orthorhombic, Pnmm, Z¼2, rcalcd¼1.733 g cmꢁ3
,
m
¼2.741 mmꢁ1
,
Mo
Ka
radiation
(l¼0.71069 Å), T¼123(2) K,
2
qmax¼27.48ꢀ, 9778 reflections measured, 1790 independent re-
flections (Rint¼0.0292), of which 1551 had I>2 (I). R(all)¼0.0323,
s
wR(all)¼0.0642, gof¼0.986, residual electron density in the range
1.720 to ꢁ0.506 e Åꢁ3. Crystallographic data (excluding structure
factors) for the structure in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publica-
tion no. CCDC 741335. Copies of the data can be obtained, free of
charge, on application to CCDC, 12 Union Road, Cambridge CB2 1EZ,
3.3. Example of catalytic reactivity of 2dTable 3, entry 14c, 9-
methanesulfonyl-2,3,4,4a,9,9a-hexahydro-1H-carbazole (15c)
Cobalt complex 12(II) (0.018 g, 2.43ꢂ10ꢁ5 mol), N-cyclohex-2-
enyl-N-(2-iodophenyl)methanesulfonamide (14c) (0.103 g, 2.77ꢂ
10ꢁ4 mol) and 1,4-cyclohexadiene (0.213 g, 2.66ꢂ10ꢁ3 mol) were
dissolved in DMF (10 ml containing 50 mM tetrabutylammonium
Acknowledgements
We thank EPSRC and WestCHEM for funding, and the EPSRC
National Mass Spectrometry Service Swansea for mass spectra.