Supporting Information
Reduction of Ketones with Silanes Catalysed by a Cyclopentadienyl-Functionalised
N-Heterocyclic Iron Complex
Rita Lopes · João M. S. Cardoso · Lorena Postigo · Beatriz Royo*
Instituto de Tecnologia Química e Biológica da Universidade Nova de Lisboa, Av. da
República, EAN, 2780-157 Oeiras, Portugal
e-mail: broyo@itqb.unl.pt
Table of Contents:
1. Experimental Section
page 2
1.1. General Procedures
1.2. General Procedure for the Catalytic Reduction of Ketones with Catalyst 4
1.3. Reaction of 2 with KOH
2. References
page 3
3. NMR spectra
page 3
3.1. NMR spectra of complex 4
page 3-4
3.2. 1H NMR spectra of the reaction of 4 with PhSiH3
page 5
3.3 1H NMR spectra of the alcohols
page 5-9
1
1.
Experimental Section
1.1.
General Procedures
All experiments were carried out under dry nitrogen using standard Schlenk techniques.
Solvents were dried by standard methods and distilled under nitrogen. 1H NMR and 13C
NMR spectra were recorded on a Bruker Avance III 400 MHz spectrometer at room
temperature and referenced to the residual 1H and
13
C signals of the solvents. Infrared
(IR) spectra were recorded on samples as KBr pellets or in toluene solutions using a
Bruker IFS 66/s spectrometer. Iron complexes 2 and 3 were prepared following the
synthetic procedure reported by us [1].
1.2.
General Procedure for the Catalytic Reduction of Ketones with Catalyst 4
A dried J. Young tube equipped with a Teflon screw cap was flushed with nitrogen and
charged with complex 2 (0.5 mol%) in 0.3 mL of deuterated toluene and KOtBu (0.5
mol%) was added at once. After one hour at room temperature, the 1H NMR of the
mixture reaction was recorded to confirm that complex 2 was completely transformed
into 4. Then, the corresponding ketone (1.0 mmol) and net silane (1.20 mmol) were
added. The samples were monitored periodically by 1H NMR. When the reaction was
completed, the mixture was treated with 1 mL of MeOH and 10 mL of an aqueous
NaOH solution (2M). The resulting mixture was stirred for several hours and
subsequently extracted with dichloromethane (3 x 20 mL). The combined organic layer
was dried with Na2SO4 and the solvent was removed under vacuum. The crude product
was treated with 2-propanol and purified by column chromatography to yield the
corresponding alcohols. The analytic data of the corresponding alcohols are in
agreement with literature data [2-6].
1.3.
Reaction of 2 with KOH
10-Fold excess of KOH (162 mg, 2.88 mmol) was added to a THF (5 mL) solution of
complex 2 (120 mg, 0.28 mmol). The reaction mixture was stirred for 24 h at 30ºC. The
solution was then filtered through celite and all the volatiles were removed under
vacuum. The residue was extracted with toluene to afford complex 4, isolated as a
brown solid.
2
2.
References
1. Cardoso JMS, Royo B (2012) Chem Commun 48:4944
2. Dieskau AP, Begouin JM, Plietker B (2011) Eur J Org Chem 5291
3. Query IP, Squier PA, Larson EM, Isley NA, Clark TB (2011) J Org Chem 76:6452
4. Wang SW, Qian HM, Yao W, Zhang LJ, Zhou SL, Yang GS, Zhu XC, Fan JX, Liu
YY, Chen GD, Song HB (2008) Polyhedron 27:2757
5. Liu SL, Wolf C (2007) Org Lett 9:2965
6. Kobayashi Y, Hayashi N, Kishi Y (2002) Org Lett 4:41
3.
NMR spectra
3.1. NMR spectra of complex 4
PPM
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7.6
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Fig. 1 1H-NMR spectrum of reaction of 4 in THF-d8
3
3.6
3.2
2.8
2.4
1.7697
1.7522
1.7437
1.7364
1.7290
1.7206
1.6895
1.3489
1.1102
2.2681
2.6429
2.8408
3.7032
3.6393
3.6275
3.5955
3.5801
3.5645
3.5434
4.2462
4.5807
4.8112
6.2963
6.2155
7.6446
7.6253
7.3512
7.3459
7.3375
7.2636
7.2574
7.2485
7.2381
7.1460
7.1290
7.1092
7.0761
7.0619
7.0499
7.0310
7.0281
7.0174
7.0023
6.9747
6.8742
8.8008
SpinWorks 2.5:
2.0
1.6
1.2
0.8
Fig. 2
13
C-NMR spectrum of 4 in THF-d8
Fig. 3 HSQC 1H-13C NMR spectrum of 4 in THF-d8
4
3.2. 1H NMR spectra of the reaction of 4 with PhSiH3
-14.0
-12.0
-10.0
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
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-12.7264
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number of scans: 64
Fig. 4. 1H-NMR spectrum of the crude reaction of 4 with PhSiH3 carried out in an NMR
tube in C6D6.
3.3 1H NMR spectra of the alcohols
PPM
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7.2
6.8
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6.0
Fig. 5 1H-NMR in CDCl3
5.6
5.2
4.8
4.4
4.0
3.6
3.2
freq. of 0 ppm: 400.135057 MHz
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5
2.8
2.4
2.0
1.3930
1.3768
2.0112
4.7976
4.7815
4.7654
4.7493
7.2806
7.2748
7.2600
7.2547
7.2441
7.2239
7.1897
7.1841
7.1765
7.1682
7.1603
7.1526
7.1481
SpinWorks 2.5: acetofenona 16 horas
1.6
1.2
0.8
0.4
1.2026
1.1874
1.5053
1.4891
1.9474
2.1580
4.0110
4.9632
4.9471
7.2601
7.6089
7.5888
7.4918
7.4717
SpinWorks 2.5: CF3acetofenona apos trat.basico CDCl3
*2-propanol
*
*
6.8
6.4
6.0
5.6
5.2
4.8
4.4
Fig. 6 1H-NMR in CDCl3
3.6
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
2.1686
4.8756
4.8598
CDCl3
7.2601
7.2407
7.4786
7.4602
4.0
freq. of 0 ppm: 400.135013 MHz
processed size: 32768 complex points
LB: 0.000 GB: 0.0000
1.2133
1.1989
7.2
1.4791
1.4638
7.6
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of scans: 16
SpinWorks
2.5: Br-acetofenona apos trat.basico
1.8302
PPM
*2-propanol
*
*
PPM
7.2
6.8
6.4
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number of scans: 16
6.0
Fig. 7 1H-NMR in CDCl3
5.6
5.2
4.8
4.4
4.0
3.6
freq. of 0 ppm: 400.135012 MHz
processed size: 32768 complex points
LB: 0.000 GB: 0.0000
6
3.2
2.8
2.4
2.0
1.6
1.2
0.8
1.2316
1.2175
1.5085
1.4933
2.3161
3.8234
4.8696
4.8546
6.9210
6.9014
6.8415
7.3314
7.3119
7.2509
SpinWorks 2.5: MeO-acetofenona +0.5mmolmesitylene 16h workup CDCl3
*2-propanol
*
*
PPM
7.2
6.8
6.4
6.0
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4.8
4.4
4.0
3.6
3.2
2.8
2.4
2.0
1.6
1.2
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Fig. 8 1H-NMR in CDCl3, (
Signals of mesitylene used as internal standard)
PPM
6.8
6.4
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1
6.0
5.6
5.2
Fig. 9 H-NMR in CDCl3, , (
4.8
4.4
4.0
3.6
3.2
freq. of 0 ppm: 400.135159 MHz
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2.8
2.4
2.0
1.6
1.2
Signals of mesitylene used as internal standard)
7
0.8665
0.8516
1.1435
1.1279
1.9539
3.6770
3.6623
4.5793
4.5641
6.4774
7.2752
7.2557
7.1413
7.1218
SpinWorks 2.5: CN-acetofenone 16h workup+0.5mmol mesitylene CDCl3
0.8
0.4
.
PPM
7.6
7.2
6.8
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4.8
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3.6
3.2
2.8
2.4
2.0
1.6
1.0734
1.0574
1.3228
1.3069
2.1436
2.3382
3.9079
3.8932
3.8781
3.8629
3.8475
3.8323
3.8175
4.6464
4.6304
6.6625
6.5353
6.5070
6.4865
7.0314
7.0117
7.6462
7.6262
SpinWorks 2.5: NH2-acetofenone 16h apos workup CDCl3
1.2
0.8
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Fig. 10 1H-NMR in CDCl3, (
Signals of mesitylene used as internal standard)
1.3800
1.3722
1.2361
1.2108
1.1840
1.1423
1.1132
1.0849
1.0595
1.5870
1.7115
2.1425
3.7039
3.7028
6.6648
SpinWorks 2.5: cyclohexanona +0.5mmol mesitylene CDCl3
OH
PPM
6.8
6.4
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1
6.0
5.6
5.2
Fig. 11 H-NMR in CDCl3, (
4.8
4.4
4.0
3.6
3.2
freq. of 0 ppm: 400.135094 MHz
processed size: 32768 complex points
LB: 0.300 GB: 0.0000
2.8
2.4
2.0
1.6
1.2
Signals of mesitylene used as internal standard)
8
0.8
0.3257
0.3205
0.3186
0.3129
0.1850
0.4711
0.5655
0.5641
0.5623
0.5579
0.9594
1.3193
1.2541
1.2521
2.3326
3.5112
5.3165
6.8566
7.2588
SpinWorks 2.5: cyclopropketone antigo +0.5mmol mesitylene CDCl3
OH
PPM
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7.2
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Fig. 12 1H-NMR in CDCl3, (
4.8
4.4
4.0
3.6
3.2
2.8
2.4
2.0
1.6
1.2
0.8
0.4
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Signals of mesitylene used as internal standard)
0.1935
0.9673
1.2492
1.3775
1.5651
2.3377
4.0803
5.3128
6.8600
7.2597
SpinWorks 2.5: hexanona antigo+0.5mmol mesitylene CDCl3
OH
PPM
7.2
6.8
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6.4
6.0
5.6
5.2
Fig. 13 1H-NMR in CDCl3, (
4.8
4.4
4.0
3.6
3.2
freq. of 0 ppm: 400.135012 MHz
processed size: 32768 complex points
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2.8
2.4
2.0
1.6
1.2
0.8
Signals of mesitylene used as internal standard)
9
0.4