New Chiral Phosphoramidite Complexes of Iron as Catalytic Precursors in the Oxidation of Activated Methylene Groups
Abstract
:1. Introduction
2. Results and Discussion
2.1. Synthesis of the Iron Phosphoramidite Complexes
Empirical formula | C40H31BrFeNO3P (CH2Cl2)2 | C40H31FeINO3P (C6H14) |
---|---|---|
Formula weight | 910.24 | 873.55 |
Temperature, Wavelength | 100(2) K, 0.71073 Å | 100(2) K, 0.71073 Å |
Crystal system, Space group | Orthorhombic, P212121 | Orthorhombic, P212121 |
Unit cell dimensions | a = 10.3609(5) Å | a = 10.2311(8) Å |
b = 17.6708(8) Å | b = 14.9124(11) Å | |
c = 21.2889(10) Å | c = 26.1055(19) Å | |
α = β = γ = 90 ° | α = β = γ = 90 ° | |
Volume, Z | 3897.7(3) Å3, 4 | 3982.9(5) Å3, 4 |
Density (calculated) | 1.551 Mg/m3 | 1.457 Mg/m3 |
Absorption coefficient | 1.769 mm−1 | 1.236 mm−1 |
Crystal size | 0.57 x 0.13 x 0.08 mm3 | 0.31 x 0.07 x 0.06 mm3 |
Theta range for data collection | 1.50 to 26.78° | 2.07 to 24.99° |
Reflections collected | 40286 | 56634 |
Independent reflections | 8268 [R(int) = 0.0520] | 7016 [R(int) = 0.1303] |
Absorption correction | Semi-empirical from equivalents | Semi-empirical from equivalents |
Max. and min. transmission | 0.8714 and 0.4316 | 0.9340 and 0.7044 |
Data / restraints / parameters | 8268 / 0 / 478 | 7016 / 72 / 472 |
Goodness-of-fit on F2 | 1.02 | 1.06 |
Final R indices [I>2sigma(I)] | R1 = 0.0304, wR2 = 0.0555 | R1 = 0.0566, wR2 = 0.1052 |
R indices (all data) | R1 = 0.0444, wR2 = 0.0593 | R1 = 0.0922, wR2 = 0.1176 |
Absolute structure parameter | 0.003(5) | 0.04(3) |
Largest diff. peak and hole | 0.553 and -0.353 e.Å−3 | 0.993 and -0.932 e.Å−3 |
Complex 4b (X=Br, Y=1) | 5b (X=I, Y=6) | 6 (X=Br) | 7 (X=Br) | 8 (X=I) | |
---|---|---|---|---|---|
X-Fe | 2.4399(5) | 2.5992(13) | 2.437(0) | 2.433 | 2.605(2) |
Fe-C(Y) | 1.778(3) | 1.770(10) | 1.744(3) | 1.740 | 1.764(6) |
C(Y)-O(1) | 1.118(3) | 1.149(10) | 1.136(4) | 1.195 | 1.077(7) |
Fe-P | 2.1501(7) | 2.150(3) | 2.163(1) | 2.201 | 2.149(2) |
P-N | 1.642(2) | 1.632(7) | - | - | |
C(Y)-Fe-P | 90.76(8) | 91.1(3) | 95.0(1) | 95.20 | 92.9(2) |
C(Y)-Fe-X | 93.17(9) | 89.5(3) | 96.02 | 91.47 | 92.8(2) |
P-Fe-X | 92.03(2) | 95.58(8) | 91.73(3) | 96.20 | 93.3(1) |
O(1)-C(Y)-Fe | 176.5(2) | 177.8(7) | 176.06 | 170.20 | 177.3(7) |
N-P-Fe | 121.54(8) | 121.0(3) | - | - | - |
O(3)-P-O(2) | 100.36(9) | 100.0(3) | 104.32 | - | - |
2.2. Application of the New Iron Phosphoramidite Complex 4a in Catalysis
Entry | Substrate | Oxidant a | Time / Temperature | Catalyst Loading | Solvent | Product | Yield (%) b |
---|---|---|---|---|---|---|---|
1 | toluene | t-BuOOH | 48 h / 90 °C | 2 mol% 4a | pyridine | NR e | |
2 | cinnamyl alcohol | t-BuOOH | 24 h / 80 °C | – | acetonitrile | cinnamaldehyde | 30 |
3 | cinnamyl alcohol | H2O2 | 24 h / rt | 10 mol% 4a | CH2Cl2 | benzaldehyde | 100 |
4 | cinnamyl alcohol | t-BuOOH | 24 h / rt | 10 mol% 4a | pyridine | cinnamaldehyde benzaldehyde | 80 ~20 |
5 | tetrahydro-naphthalene | t-BuOOH | 18 h / 90 °C | 2 mol% 4a | pyridine | tetrahydronaph-thalene-1-one | 100 |
6 | tetrahydronaph-thalene-1-ol | t-BuOOH | 16 h / rt | – | pyridine | tetrahydronaph-thalene-1-one | 100 |
7 | diphenyl-methane | t-BuOOH | 36 h / 82 °C | 2 mol% 4a | pyridine | benzophenone | 100 |
8 | fluorene | t-BuOOH | 36 h / rt | 2 mol% 4a | pyridine | fluorenone | 100 |
9 | fluorene | mCPBA c | 36 h / rt | 2 mol% 4a | pyridine | fluorenone | traces |
10 | fluorene | CH3COOOH d | 36 h / rt | 2 mol% 4a | pyridine | fluorenone | traces |
11 | fluorene | t-BuOOH | 36 h / rt | 2 mol% 4a | pyridine | fluorenone | 100 |
12 | dihydro-anthracene | t-BuOOH | 36 h / rt | 2 mol% 4a | pyridine | anthraquinone | 100 |
13 | adamantane | t-BuOOH | 36 h / rt | 2 mol% 4a | pyridine | NR e | |
14 | adamantane | t-BuOOH | 36 h / 90 °C | 2 mol% 4a | pyridine | NR e | |
15 | diphenyl-methane | H2O2 | 36 h / rt | 10 mol% 4a | CH2Cl2 | NR e | |
16 | cyclooctene | t-BuOOH | 42 h / rt | 2 mol% 4a | pyridine | NR e | |
17 | fluorene | t-BuOOH | 36 h / rt | 2 mol% 2 | pyridine | fluorenone | 30 |
18 | dihydro-anthracene | t-BuOOH | 36 h / rt | 2 mol% 2 | pyridine | anthraquinone | 9 f |
19 | diphenyl-methane | t-BuOOH | 36 h / rt | 2 mol% 2 | pyridine | benzophenone | 27 |
20 | fluorene | t-BuOOH | 36 h / rt | 2 mol% 3 | pyridine | fluorenone | 21 |
Entry | Starting Material | Product | Yield b | TOF / h−1 c |
---|---|---|---|---|
1 | diphenylmethane | benzo-phenone | 56% | 0.78 |
2 | fluorene | fluorenone | 80% | 1.11 |
3 | dihydroanthracene | anthra-quinone | 54% d | 1.39 |
4 | cinnamylalcohol | cinnamyl aldehyde | 31% e | 0.37 e |
5 | phenylmethanol | benzaldehyde | 47% e | 0.56 e |
2.3. Further Experiment to Better Understand the Oxidation Reactions
3. Experimental
3.1. General
3.2. Synthesis of “[FeBrCp(CO)(1a)]”, 4a
3.3. Synthesis of “[FeBrCp(CO)(1b)]”, 4b
3.4. Attempted synthesis of “[FeBrCp(CO)(1c)]”, 4c
3.5. Synthesis of “[Fe(Cp)I(CO)(1b)]”, 5b
3.6. Typical Procedure for the Catalytic Experiments
3.7. Monitoring of the Oxidation of Fluorene to Fluorenone over Time (Figure 5)
3.8. Reaction of the Catalyst 4a with the Oxidant t-BuOOH without Substrate.
3.9. X-ray Structure Determination for 4b and 5b
4. Conclusions
Supplementary Materials
Acknowledgments
References and Notes
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Shejwalkar, P.; Rath, N.P.; Bauer, E.B. New Chiral Phosphoramidite Complexes of Iron as Catalytic Precursors in the Oxidation of Activated Methylene Groups. Molecules 2010, 15, 2631-2650. https://doi.org/10.3390/molecules15042631
Shejwalkar P, Rath NP, Bauer EB. New Chiral Phosphoramidite Complexes of Iron as Catalytic Precursors in the Oxidation of Activated Methylene Groups. Molecules. 2010; 15(4):2631-2650. https://doi.org/10.3390/molecules15042631
Chicago/Turabian StyleShejwalkar, Pushkar, Nigam P. Rath, and Eike B. Bauer. 2010. "New Chiral Phosphoramidite Complexes of Iron as Catalytic Precursors in the Oxidation of Activated Methylene Groups" Molecules 15, no. 4: 2631-2650. https://doi.org/10.3390/molecules15042631